Prediction of small-for-gestational-age neonates: screening by fetal biometry at 35-37 weeks

Prediction of small-for-gestational age and fetal growth restriction at routine ultrasound examination at 35-37 weeks' gestation

OBJECTIVE

To evaluate the performance of sonographic fetal biometry and Doppler parameters assessed at routine third-trimester ultrasound examination for predicting small-for-gestational age (SGA) and fetal growth restriction (FGR).

METHODS

This was a retrospective cohort study of low-risk singleton pregnancies undergoing routine ultrasound examination between 35 + 0 and 37 + 6 weeks' gestation and delivered at St George's University Hospital, London, UK, between December 2019 and February 2024. The study outcomes were SGA (birth weight < 5th centile) and FGR (birth weight < 3rd centile or birth weight < 10th centile with composite adverse perinatal outcome). Composite adverse perinatal outcome comprised intrauterine death, neonatal death or admission to the neonatal intensive care unit. Demographic characteristics, estimated fetal weight (EFW) and abdominal circumference centiles, as well as Doppler indices, including pulsatility indices (PI) of the umbilical artery (UA), middle cerebral artery (MCA) and uterine artery (UtA) were evaluated. The cerebroplacental ratio (CPR) was calculated, and all indices were converted to multiples of the median (MoM). Multivariable logistic regression analysis was performed to identify and adjust for confounders. The area under the receiver-operating-characteristics curve (AUC) was used to evaluate the model's performance for predicting small neonates.

RESULTS

A total of 14 161 pregnancies were included in the study. The prevalence of SGA and FGR neonates was 3.1% and 1.5%, respectively. Independent predictors of SGA and FGR, respectively, were: EFW centile (adjusted odds ratio (aOR) 0.91 (95% CI, 0.90-0.92); P < 0.001 and aOR 0.90 (95% CI, 0.89-0.91); P < 0.001); AC centile (aOR 0.91 (95% CI, 0.90-0.92); P < 0.001 and aOR 0.91 (95% CI, 0.90-0.92); P <0.001); UA-PI MoM (aOR 4.60 (95% CI, 2.19-9.64); P < 0.001 and aOR 2.53 (95% CI, 1.05-6.10); P = 0.038); MCA-PI MoM (aOR 0.37 (95% CI, 0.20-0.70); P = 0.002 and aOR 0.26 (95% CI, 0.12-0.59); P = 0.001); CPR MoM (aOR 0.23 (95% CI, 0.13-0.42); P < 0.001 and aOR 0.25 (95% CI, 0.12-0.53); P < 0.001); and UtA-PI MoM (aOR 2.54 (95% CI, 1.68-3.83); P < 0.001 and aOR 2.16 (95% CI, 1.31-3.58); P = 0.003). The EFW centile alone was associated with an AUC of 0.917 (95% CI, 0.907-0.929) for the prediction of SGA and 0.925 (95% CI, 0.908-0.939) for the prediction of FGR. This was similar to AUCs of around 0.92 for the prediction of SGA and AUCs of around 0.93 for the prediction of FGR when the EFW centile was combined with any Doppler parameters.

CONCLUSIONS

Sonographic fetal biometry evaluation in the late third trimester can predict delivery of a neonate affected by SGA or FGR, including those at risk for adverse perinatal outcomes. In an unselected population, fetal arterial Doppler parameters were independent predictors of SGA and FGR, but the addition of Doppler parameters to fetal biometry did not improve prediction of the incidence of small neonates. © 2025 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

3rd trimester ultrasound assessment

The third-trimester scan allows not only the assessment of foetal growth but also its presentation and anatomy, and placental, amniotic fluid, and umbilical cord anomalies. Although there is a great disparity when considering its recommendation, most recent studies raise the question for its usefulness considering its impact in a potential reduction of perinatal morbidity and mortality. For this to be a reality in a population-wide setting, a systematic approach should be made considering performing it between 35 + 0 and 36 + 6 weeks', including the assessment of estimated foetal weight, foetal Doppler (umbilical and middle cerebral artery), placenta, amniotic fluid, foetal anatomy, and presentation. In high-risk cases, additional evaluation of the placenta, umbilical cord, or advanced foetal anatomy assessment can be warranted. Furthermore, pre-defined and evidence-based protocols should be followed after anomalies are detected in order to improve maternal and perinatal outcomes.

Routine 36-week scan: prediction of small-for-gestational-age neonate

OBJECTIVES

First, to compare the predictive performance of routine ultrasonographic estimated fetal weight (EFW) at 31 + 0 to 33 + 6 and 35 + 0 to 36 + 6 weeks' gestation for delivery of a small-for-gestational-age (SGA) neonate. Second, to compare the predictive performance of EFW at 36 weeks' gestation for SGA vs fetal growth restriction (FGR) at birth. Third, to compare the predictive performance for delivery of a SGA neonate of EFW < 10th percentile vs a model combining maternal demographic characteristics and elements of medical history with EFW.

METHODS

This was a retrospective analysis of prospectively collected data in 21 676 women with a singleton pregnancy who had undergone routine ultrasound examination at 31 + 0 to 33 + 6 weeks' gestation and 107 875 women with a singleton pregnancy who had undergone routine ultrasound examination at 35 + 0 to 36 + 6 weeks. Measurements of fetal head circumference, abdominal circumference and femur length were used to calculate EFW according to the Hadlock formula and this was expressed as a percentile according to the Fetal Medicine Foundation fetal and neonatal population weight charts. The same charts were used to diagnose SGA neonates with birth weight < 10th or < 3rd percentile. FGR was defined as birth weight < 10th percentile in addition to Doppler anomalies. For each gestational-age window at screening, the screen-positive rate and detection rate were calculated at different EFW cut-offs between the 10th and 50th percentiles for predicting the delivery of a SGA neonate with birth weight < 10th or < 3rd percentile, either within 2 weeks or at any time after assessment. The areas under the receiver-operating-characteristics curves (AUC) of screening for a SGA neonate by EFW at 31 + 0 to 33 + 6 weeks and at 35 + 0 to 36 + 6 weeks were compared.

RESULTS

The predictive performance of routine ultrasonographic examination during the third trimester for delivery of a SGA neonate is higher if: first, the scan is carried out at 35 + 0 to 36 + 6 weeks' gestation rather than at 31 + 0 to 33 + 6 weeks; second, the outcome measure is birth weight < 3rd rather than < 10th percentile; third, the outcome measure is FGR rather than SGA; fourth, if delivery occurs within 2 weeks after assessment rather than at any time after assessment; and fifth, prediction is performed using a model that combines maternal demographic characteristics and elements of medical history with EFW rather than EFW < 10th percentile alone. At 35 + 0 to 36 + 6 weeks' gestation, detection of ≥ 85% of SGA neonates with birth weight < 10th percentile born at any time after assessment necessitates the use of EFW < 40th percentile. Screening at this percentile cut-off predicted 95% and 98% of neonates with birth weight < 10th and < 3rd percentile, respectively, born within 2 weeks after assessment, and the respective values for neonates born at any time after assessment were 85% and 93%.

CONCLUSION

Routine third-trimester ultrasonographic screening for a SGA neonate performs best when the scan is carried out at 35 + 0 to 36 + 6 weeks' gestation, rather than at 31 + 0 to 33 + 6 weeks, and when EFW is combined with maternal risk factors to estimate the patient-specific risk. © 2024 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Neonatal Outcomes among Fetuses with an Abdominal Circumference <3rd %ile and Estimated Fetal Weight 3rd to 9th %ile Compared to Fetuses with an EFW <3rd %ile

OBJECTIVE

Fetal growth restriction (FGR) is defined as an estimated fetal weight (EFW) or abdominal circumference (AC) <10th percentile (%ile) for gestational age (GA). An EFW <3rd %ile for GA is considered severe FGR (sFGR). It remains unknown if fetuses with isolated AC <3rd %ile should be considered sFGR. Our primary objective was to assess composite neonatal outcomes in fetuses with an AC <3rd %ile and overall EFW 3rd to 9th %ile compared with those with an EFW <3rd %ile.

STUDY DESIGN

This retrospective cohort study was undertaken at a tertiary academic center from January 2016 to December 2021. Inclusion criteria were singleton fetuses with an EFW <3rd %ile (Group 1) or AC <3rd %ile with EFW 3rd to 9th %ile (Group 2) at 28 weeks' gestation or greater. Exclusion criteria were multiple gestations, presence of a major fetal anomaly, resolution of FGR, genetic syndrome, or infection. Composite neonatal outcome was defined by any of the following: neonatal intensive care unit admission >48 hours, necrotizing enterocolitis, sepsis, respiratory distress syndrome, mechanical ventilation, retinopathy of prematurity, seizures, intraventricular hemorrhage, stillbirth, or death before discharge. Small for gestational age (SGA) was defined as birth weight <10th %ile for GA.

RESULTS

A total of 743 patients fulfilled our study criteria, with 489 in Group 1 and 254 in Group 2. The composite neonatal outcome occurred in 281 (57.5%) neonates in Group 1 and 53 (20.9%) in Group 2 (p < 0.01). The rates of SGA at birth were 94.9 and 75.6% for Group 1 and Group 2, respectively (OR 5.99, 95% confidence interval 3.65-9.82).

CONCLUSION

Although AC <3rd %ile with EFW 3rd to 9th %ile is associated with a lower frequency of SGA and neonatal morbidity than EFW <3 %ile, fetuses with AC <3 %ile still exhibited moderate rates of these adverse perinatal outcomes. Consideration should be given to inclusion of an AC <3rd %ile with EFW 3rd to 9th %ile as a criterion for sFGR. However, prospective studies comparing delivery at 37 versus 38 to 39 weeks' gestation are needed to ensure improved outcomes before widespread adaptation in clinical practice.

KEY POINTS

· The composite neonatal outcome occurred in 57.5% of fetuses with an overall EFW <3rd %ile and 20.9% of fetuses with an AC <3rd %ile but EFW 3rd to 9th %ile.. · Both groups demonstrated a high positive predictive value for SGA birth weight.. · Consideration should be given to inclusion of an AC <3rd %ile as a criterion for sFGR..

Indicated vs universal third-trimester ultrasound examination in low-risk pregnancies: a pre-post-intervention study

BACKGROUND

In low-risk pregnancies, a third-trimester ultrasound examination is indicated if fundal height measurement and gestational age discrepancy are observed. Despite potential improvement in the detection of ultrasound abnormality, prior trials to date on universal third-trimester ultrasound examination in low-risk pregnancies, compared with indicated ultrasound examination, have not demonstrated improvement in neonatal or maternal adverse outcomes.

OBJECTIVE

The primary objective was to determine if universal third-trimester ultrasound examination in low-risk pregnancies could attenuate composite neonatal adverse outcomes. The secondary objectives were to compare changes in composite maternal adverse outcomes and detection of abnormalities of fetal growth (fetal growth restriction or large for gestational age) or amniotic fluid (oligohydramnios or polyhydramnios).

STUDY DESIGN

Our pre-post intervention study at 9 locations included low-risk pregnancies, those without indication for ultrasound examination in the third trimester. Compared with indicated ultrasound in the preimplementation period, in the postimplementation period, all patients were scheduled for ultrasound examination at 36.0-37.6 weeks. In both periods, clinicians intervened on the basis of abnormalities identified. Composite neonatal adverse outcomes included any of: Apgar score ≤5 at 5 minutes, cord pH <7.00, birth trauma (bone fracture or brachial plexus palsy), intubation for >24 hours, hypoxic-ischemic encephalopathy, seizure, sepsis (bacteremia proven with blood culture), meconium aspiration syndrome, intraventricular hemorrhage grade III or IV, periventricular leukomalacia, necrotizing enterocolitis, stillbirth after 36 weeks, or neonatal death within 28 days of birth. Composite maternal adverse outcomes included any of the following: chorioamnionitis, wound infection, estimated blood loss >1000 mL, blood transfusion, deep venous thrombus or pulmonary embolism, admission to intensive care unit, or death. Using Bayesian statistics, we calculated a sample size of 600 individuals in each arm to detect >75% probability of any reduction in primary outcome (80% power; 50% hypothesized risk reduction).

RESULTS

During the preintervention phase, 747 individuals were identified during the initial ultrasound examination, and among them, 568 (76.0%) met the inclusion criteria at 36.0-37.6 weeks; during the postintervention period, the corresponding numbers were 770 and 661 (85.8%). The rate of identified abnormalities of fetal growth or amniotic fluid increased from between the pre-post intervention period (7.1% vs 22.2%; P<.0001; number needed to diagnose, 7; 95% confidence interval, 5-9). The primary outcome occurred in 15 of 568 (2.6%) individuals in the preintervention and 12 of 661 (1.8%) in the postintervention group (83% probability of risk reduction; posterior relative risk, 0.69 [95% credible interval, 0.34-1.42]). The composite maternal adverse outcomes occurred in 8.6% in the preintervention and 6.5% in the postintervention group (90% probability of risk; posterior relative risk, 0.74 [95% credible interval, 0.49-1.15]). The number needed to treat to reduce composite neonatal adverse outcomes was 121 (95% confidence interval, 40-200). In addition, the number to reduce composite maternal adverse outcomes was 46 (95% confidence interval, 19-74), whereas the number to prevent cesarean delivery was 18 (95% confidence interval, 9-31).

CONCLUSION

Among low-risk pregnancies, compared with routine care with indicated ultrasound examination, implementation of a universal third-trimester ultrasound examination at 36.0-37.6 weeks attenuated composite neonatal and maternal adverse outcomes.

Diagnostic performance of 32 vs 36 weeks ultrasound in predicting late-onset fetal growth restriction and small-for-gestational-age neonates: a systematic review and meta-analysis

OBJECTIVE

Fetal growth restriction is an independent risk factor for fetal death and adverse neonatal outcomes. The main aim of this study was to investigate the diagnostic performance of 32 vs 36 weeks ultrasound of fetal biometry in detecting late-onset fetal growth restriction and predicting small-for-gestational-age neonates.

DATA SOURCES

A systematic search was performed to identify relevant studies published until June 2022, using the databases PubMed, Web of Science, and Scopus.

STUDY ELIGIBILITY CRITERIA

Cohort studies in low-risk or unselected singleton pregnancies with screening ultrasound performed at ≥32 weeks of gestation were used.

METHODS

The estimated fetal weight and abdominal circumference were assessed as index tests for the prediction of small for gestational age (birthweight of <10th percentile) and detecting fetal growth restriction (estimated fetal weight of <10th percentile and/or abdominal circumference of <10th percentile). The quality of the included studies was independently assessed by 2 reviewers using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. For the meta-analysis, hierarchical summary area under the receiver operating characteristic curves were constructed, and quantitative data synthesis was performed using random-effects models.

RESULTS

The analysis included 25 studies encompassing 73,981 low-risk pregnancies undergoing third-trimester ultrasound assessment for growth, of which 5380 neonates (7.3%) were small for gestational age at birth. The pooled sensitivities for estimated fetal weight of <10th percentile and abdominal circumference of <10th percentile in predicting small for gestational age were 36% (95% confidence interval, 27%-46%) and 37% (95% confidence interval, 19%-60%), respectively, at 32 weeks ultrasound and 48% (95% confidence interval, 41%-56%) and 50% (95% confidence interval, 25%-74%), respectively, at 36 weeks ultrasound. The pooled specificities for estimated fetal weight of <10th percentile and abdominal circumference of <10th percentile in detecting small for gestational age were 93% (95% confidence interval, 91%-95%) and 95% (95% confidence interval, 85%-98%), respectively, at 32 weeks ultrasound and 93% (95% confidence interval, 91%-95%) and 97% (95% confidence interval, 85%-98%), respectively, at 36 weeks ultrasound. The observed diagnostic odds ratios for an estimated fetal weight of <10th percentile and an abdominal circumference of <10th percentile in detecting small for gestational age were 8.8 (95% confidence interval, 5.4-14.4) and 11.6 (95% confidence interval, 6.2-21.6), respectively, at 32 weeks ultrasound and 13.3 (95% confidence interval, 10.4-16.9) and 36.0 (95% confidence interval, 4.9-260.0), respectively, at 36 weeks ultrasound. The pooled sensitivity, specificity, and diagnostic odds ratio in predicting fetal growth restriction were 71% (95% confidence interval, 52%-85%), 90% (95% confidence interval, 79%-95%), and 25.8 (95% confidence interval, 14.5-45.8), respectively, at 32 weeks ultrasound and 48% (95% confidence interval, 41%-55%), 94% (95% confidence interval, 93%-96%), and 16.9 (95% confidence interval, 10.8-26.6), respectively, at 36 weeks ultrasound. Abdominal circumference of <10th percentile seemed to have comparable sensitivity to estimated fetal weight of <10th percentile in predicting small-for-gestational-age neonates.

CONCLUSION

An ultrasound assessment of the fetal biometry at 36 weeks of gestation seemed to have better predictive accuracy for small-for-gestational-age neonates than an ultrasound assessment at 32 weeks of gestation. However, an opposite trend was noted when the outcome was fetal growth restriction. Fetal abdominal circumference had a similar predictive accuracy to that of estimated fetal weight in detecting small-for-gestational-age neonates.

Fetal growth trajectories of small/large for gestational age infants in twin pregnancies

BACKGROUND

Birthweight is the most common and accessible parameter in assessing neonatal perinatal outcomes and in evaluating the intrauterine environment globally. Infants born too large or too small not only may alter the maternal mode of delivery but also may face other long-term disorders, such as metabolic diseases and neurodevelopmental delay. Studies have revealed different growth profiles of large-for-gestational-age and small-for-gestational-age fetuses in singleton pregnancies. However, currently, no research is focused on the growth trajectories of these infants during twin pregnancies, even though they are at a much higher risk of being small for gestational age.

OBJECTIVE

This study aimed to explore fetal growth trajectories of large-for-gestational-age and small-for-gestational-age infants in twin pregnancies to provide strategies for fetal growth management.

STUDY DESIGN

This was a case-control study of all noncomplicated twin pregnancies delivered after 36 weeks of gestation at the Peking University First Hospital between 2012 and 2021. Ultrasound data were recorded every 2 to 4 weeks until delivery. All the infants were divided into large-for-gestational-age, small-for-gestational-age, and appropriate-for-gestational-age groups. Longitudinal fetal growth (estimated fetal weight, abdominal circumference, etc.) was compared among the 3 groups using a linear mixed model, and other maternal and neonatal perinatal outcomes were compared. Receiver operating characteristic curves were used to explore optimal biometric parameters and gestational weeks for predicting small-for-gestational-age infants.

RESULTS

Here, 797 pregnant patients with 1494 infants were recruited, with 59 small-for-gestational-age infants, 1335 appropriate-for-gestational-age infants, and 200 large-for-gestational-age infants. The mean birthweights were 1985.34±28.34 g in small-for-gestational-age infants, 2662.08±6.60 g in appropriate-for-gestational-age infants, and 3231.24±11.04 g in large-for-gestational-age infants. The estimated fetal weight of the 3 groups differed from each other from week 26, with the small-for-gestational-age fetuses weighing 51.946 g less and the large-for-gestational-age fetuses weighing 35.233 g more than the appropriate-for-gestational-age fetuses. This difference increased with gestation; at 39 weeks, the small-for-gestational-age fetuses weighed 707.438 g less and the large-for-gestational-age fetuses weighed 614.182 g more than the appropriate-for-gestational-age fetuses (all P<.05). The small-for-gestational-age group had a significantly higher rate of hospitalization (89.9 %) and jaundice (40.7 %) than the appropriate-for-gestational-age group, whereas the hospitalization rate in the large-for-gestational-age group was significantly lower than the appropriate-for-gestational-age group (7.5% and 2.5%; all P<.05). The fetal weight of the small-for-gestational-age infants with adverse outcomes remained near the 10th percentile of the reference and fell below the 3rd percentile at 34 weeks of gestation. The estimated fetal weight after 30 weeks of gestation had a satisfactory diagnostic value in predicting small-for-gestational-age infants. At 30, 32, 34, and 36 weeks of gestation, the areas under the curve were 0.829, 0.840, 0.929, and 0.889 respectively.

CONCLUSION

The growth patterns of small-for-gestational-age, appropriate-for-gestational-age, and large-for-gestational-age twin fetuses diverged from 26 weeks of gestation and continued to increase until delivery; therefore, closer monitoring is suggested from 26 weeks of gestation for those carrying small fetuses.

Fetal Growth Restriction Is Associated with Pregnancy Associated Plasma Protein A and Uterine Artery Doppler in First Trimester

Fetal growth restriction (FGR) is a major cause of stillbirth and poor neurodevelopmental outcomes. The early prediction may be important to establish treatment options and improve neonatal outcomes. The aim of this study was to assess the association of parameters used in first-trimester screening, uterine artery Doppler pulsatility index and the development of FGR. In this retrospective cohort study, 1930 singleton pregnancies prenatally diagnosed with an estimated fetal weight under the third percentile were included. All women underwent first-trimester screening assessing maternal serum pregnancy-associated plasma protein A (PAPP-A), free beta-human chorionic gonadotrophin levels, fetal nuchal translucency and uterine artery Doppler pulsatility index (PI). We constructed a Receiver Operating Characteristics curve to calculate the sensitivity and specificity of early diagnosis of FGR. In pregnancies with FGR, PAPP-A was significantly lower, and uterine artery Doppler pulsatility index was significantly higher compared with the normal birth weight group (0.79 ± 0.38 vs. 1.15 ± 0.59, p < 0.001 and 1.82 ± 0.7 vs. 1.55 ± 0.47, p = 0.01). Multivariate logistic regression analyses demonstrated that PAPP-A levels and uterine artery Doppler pulsatility index were significantly associated with FGR (p = 0.009 and p = 0.01, respectively). To conclude, these two parameters can predict FGR < 3rd percentile.

Prediction of small-for-gestational-age neonates at 33-39 weeks' gestation in China: logistic regression modeling of the contributions of second- and third-trimester ultrasound data and maternal factors

Objectives

A screening model for prediction of small-for-gestational-age (SGA) neonates (SGAp) was established by logistic regression using ultrasound data and maternal factors (MF). We aimed to evaluate the ability of SGAp as well as abdominal circumference (AC) and estimated fetal weight (EFW) measurements to predict SGA neonates at 33–39 weeks’ gestation.

Methods

This retrospective study evaluated 5298 singleton pregnancies that had involved three ultrasound examinations at 21⁺⁰–27⁺⁶, 28⁺⁰–32⁺⁶, and 33⁺⁰–39⁺⁶ weeks. All ultrasound data were transformed to MoM values (multiple of the median). Multivariate logistic regression was used to analyze the correlation between SGA status and various variables (ultrasound data and MF) during pregnancy to build the SGAp model. EFW was calculated according to the Hadlock formula at 33–39 weeks of gestation. The predictive performance of SGAp, AC MoM value at 33⁺⁰–39⁺⁶ weeks (AC-M), EFW MoM value (EFW-M), EFW-M plus MF, AC value at 33⁺⁰–39⁺⁶ weeks (AC), AC growth velocity, EFW, and EFW plus MF was evaluated using ROC curves. The detection rate (DR) of SGA neonate with SGAp, AC-M, EFW-M, and EFW-M plus MF at false positive rate (FPR) of 5% and 10%, and the FPR at DR of 85%, 90%, and 95% were observed.

Results

The AUCs of SGAp, AC-M, EFW-M, EFW-M plus MF, AC, AC growth velocity, EFW, and EFW plus MF for SGA neonates screening were 0.933 (95%CI: 0.916–0.950), 0.906 (95%CI: 0.887–0.925), 0.920 (95%CI: 0.903–0.936), 0.925 (95%CI: 0.909–0.941), 0.818 (95%CI: 0.791–0.845), 0.786 (95%CI: 0.752–0.821), 0.810 (95%CI: 0.782–0.838), and 0.834 (95%CI: 0.807–0.860), respectively. The screening efficiency of SGAp, AC-M, EFW-M, and EFW-M plus MF are significantly higher than AC, AC growth velocity, EFW, and EFW plus MF. The DR of SGAp, AC-M, EFW-M, and EFW-M plus MF for SGA neonates were 80.4%, 69.6%, 73.8% and 74.3% at 10% FPR. The AUCs of SGAp, AC-M, EFW-M, and EFW-M plus MF 0.950 (95%CI: 0.932–0.967), 0.929 (95%CI: 0.909–0.948), 0.938 (95%CI: 0.921–0.956) and 0.941 (95%CI: 0.924–0.957), respectively for screening SGA neonates delivered within 2 weeks after the assessment. The DR for these births increased to 85.8%, 75.8%, 80.0%, and 82.5%, respectively.

Conclusion

The rational use of ultrasound data can significantly improve the prediction of SGA statuses.

Personalized Model to Predict Small for Gestational Age at Delivery Using Fetal Biometrics, Maternal Characteristics, and Pregnancy Biomarkers: A Retrospective Cohort Study of Births Assisted at a Spanish Hospital

Small for gestational age (SGA) is defined as a newborn with a birth weight for gestational age < 10th percentile. Routine third-trimester ultrasound screening for fetal growth assessment has detection rates (DR) from 50 to 80%. For this reason, the addition of other markers is being studied, such as maternal characteristics, biochemical values, and biophysical models, in order to create personalized combinations that can increase the predictive capacity of the ultrasound. With this purpose, this retrospective cohort study of 12,912 cases aims to compare the potential value of third-trimester screening, based on estimated weight percentile (EPW), by universal ultrasound at 35−37 weeks of gestation, with a combined model integrating maternal characteristics and biochemical markers (PAPP-A and β-HCG) for the prediction of SGA newborns. We observed that DR improved from 58.9% with the EW alone to 63.5% with the predictive model. Moreover, the AUC for the multivariate model was 0.882 (0.873−0.891 95% C.I.), showing a statistically significant difference with EPW alone (AUC 0.864 (95% C.I.: 0.854−0.873)). Although the improvements were modest, contingent detection models appear to be more sensitive than third-trimester ultrasound alone at predicting SGA at delivery.

Circulating SPINT1 Is Reduced in a Preeclamptic Cohort with Co-Existing Fetal Growth Restriction

Fetal growth restriction (FGR), when undetected antenatally, is the biggest risk factor for preventable stillbirth. Maternal circulating SPINT1 is reduced in pregnancies, which ultimately deliver small for gestational age (SGA) infants at term (birthweight < 10th centile), compared to appropriate for gestational age (AGA) infants (birthweight ≥ 10th centile). SPINT1 is also reduced in FGR diagnosed before 34 weeks’ gestation. We hypothesised that circulating SPINT1 would be decreased in co-existing preterm preeclampsia and FGR. Plasma SPINT1 was measured in samples obtained from two double-blind, randomised therapeutic trials. In the Preeclampsia Intervention with Esomeprazole trial, circulating SPINT1 was decreased in women with preeclampsia who delivered SGA infants (n = 75, median = 18,857 pg/mL, IQR 10,782–29,890 pg/mL, p < 0.0001), relative to those delivering AGA (n = 22, median = 40,168 pg/mL, IQR 22,342–75,172 pg/mL). This was confirmed in the Preeclampsia Intervention 2 with metformin trial where levels of SPINT1 in maternal circulation were reduced in SGA pregnancies (n = 95, median = 57,764 pg/mL, IQR 42,212–91,356 pg/mL, p < 0.0001) compared to AGA controls (n = 40, median = 107,062 pg/mL, IQR 70,183–176,532 pg/mL). Placental Growth Factor (PlGF) and sFlt-1 were also measured. PlGF was significantly reduced in the SGA pregnancies, while ratios of sFlt-1/SPINT1 and sFlt1/PlGF were significantly increased. This is the first study to demonstrate significantly reduced SPINT1 in co-existing FGR and preeclamptic pregnancies.

Development and validation of model for prediction of placental dysfunction-related stillbirth from maternal factors, fetal weight and uterine artery Doppler at mid-gestation

OBJECTIVE

To examine the performance of a model combining maternal risk factors, uterine artery pulsatility index (UtA-PI) and estimated fetal weight (EFW) at 19-24 weeks' gestation, for predicting all antepartum stillbirths and those due to impaired placentation, in a training dataset used for development of the model and in a validation dataset.

METHODS

The data for this study were derived from prospective screening for adverse obstetric outcome in women with singleton pregnancy attending for routine pregnancy care at 19 + 0 to 24 + 6 weeks' gestation. The study population was divided into a training dataset used to develop prediction models for placental dysfunction-related antepartum stillbirth and a validation dataset to which the models were then applied. Multivariable logistic regression analysis was used to develop a model based on a combination of maternal risk factors, EFW Z-score and UtA-PI multiples of the normal median. We examined the predictive performance of the model by, first, the ability of the model to discriminate between the stillbirth and live-birth groups, using the area under the receiver-operating-characteristics curve (AUC) and the detection rate (DR) at a fixed false-positive rate (FPR) of 10%, and, second, calibration by measurements of calibration slope and intercept.

RESULTS

The study population of 131 514 pregnancies included 131 037 live births and 477 (0.36%) stillbirths. There are four main findings of this study. First, 92.5% (441/477) of stillbirths were antepartum and 7.5% (36/477) were intrapartum, and 59.2% (261/441) of antepartum stillbirths were observed in association with placental dysfunction and 40.8% (180/441) were unexplained or due to other causes. Second, placental dysfunction accounted for 80.1% (161/201) of antepartum stillbirths at < 32 weeks' gestation, 54.2% (52/96) at 32 + 0 to 36 + 6 weeks and 33.3% (48/144) at ≥ 37 weeks. Third, the risk of placental dysfunction-related antepartum stillbirth increased with increasing maternal weight and decreasing maternal height, was 3-fold higher in black than in white women, was 5.5-fold higher in parous women with previous stillbirth than in those with previous live birth, and was increased in smokers, in women with chronic hypertension and in parous women with a previous pregnancy complicated by pre-eclampsia and/or birth of a small-for-gestational-age baby. Fourth, in screening for placental dysfunction-related antepartum stillbirth by a combination of maternal risk factors, EFW and UtA-PI in the validation dataset, the DR at a 10% FPR was 62.3% (95% CI, 57.2-67.4%) and the AUC was 0.838 (95% CI, 0.799-0.878); these results were consistent with those in the dataset used for developing the algorithm and demonstrate high discrimination between affected and unaffected pregnancies. Similarly, the calibration slope was 1.029 and the intercept was -0.009, demonstrating good agreement between the predicted risk and observed incidence of placental dysfunction-related antepartum stillbirth. The performance of screening was better for placental dysfunction-related antepartum stillbirth at < 37 weeks' gestation compared to at term (DR at a 10% FPR, 69.8% vs 29.2%).

CONCLUSIONS

Screening at mid-gestation by a combination of maternal risk factors, EFW and UtA-PI can predict a high proportion of placental dysfunction-related stillbirths and, in particular, those that occur preterm. Such screening provides poor prediction of unexplained stillbirth or stillbirth due to other causes. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Reduced Growth in Non-Small for Gestational Age Fetuses from 35 Weeks of Gestation to Birth and Perinatal Outcomes

OBJECTIVE

This study aimed to assess reduced fetal growth between 35 weeks of gestation and birth in non-small for gestational age fetuses associated with adverse perinatal outcomes (APOs).

MATERIAL AND METHOD

It is a retrospective cohort study of 9,164 non-small for gestational age fetuses estimated by ultrasound at 35 weeks. The difference between the birth weight percentile and the estimated percentile weight (EPW) at 35 weeks of gestation was calculated, and we studied the relationship of this difference with the appearance of APO. APOs were defined as cesarean or instrumental delivery rates for nonreassuring fetal status, 5-min Apgar score <7, arterial cord blood pH <7.10, and stillbirth. Fetuses that exhibited a percentile decrease between both moments were classified into 6 categories according to the amount of percentile decrease (0.01-10.0, 10.01-20.0, 20.01-30.0, 30.01-40.0, 40.01-50.0, and >50.0 percentiles). It was evaluated whether the appearance of APO was related to the amount of this percentile decrease. Relative risk (RR) was calculated in these subgroups to predict APOs in general and for each APO in particular. Receiver operating characteristic and area under curves (AUC) for the difference in the percentile was calculated, used as a continuous parameter in the entire study population.

RESULTS

The median gestational age at delivery in uncomplicated pregnancies was 40.0 (39.1-40.7) and in pregnancies with APOs 40.3 (49.4-41.0), p < 0.001. The prevalence of APOs was greater in the group of fetuses with a decrease in percentile (7.6%) compared to those with increased percentile (4.8%) (p < 0.001). The RR was 1.63 (95% CI: 1.365-1.944, p < 0.001). Although the differences were significant in all decreased percentile groups, RRs were significantly higher when decreased growth values were >40 points (RR: 2.036, 95% CI: 1.581-2.623, p < 0.001). The estimated value of the AUC for percentile decrease was 0.58 (0.56-0.61, p < 0.001).

CONCLUSION

Fetuses with a decrease in the EPW between the ultrasound at 35 weeks of gestation and birth have a higher risk of APOs, being double in fetuses with a decrease of >40 percentile points.

The risk of recurrent small-for-gestational-age infants at term is dependent on the number of previously affected births

BACKGROUND

Small-for-gestational-age infants are at a substantially increased risk of perinatal complications, but the risk of recurrent small-for-gestational-age is not well known, particularly because there are many demographic and obstetrical factors that interact and modify this risk. We investigated the relationship between previous small-for-gestational-age births and the risk of recurrence at term in a large Australian cohort.

OBJECTIVE

We aimed to identify key demographic and obstetrical variables that influence the risk of recurrence of a small-for-gestational-age infant at term. The primary outcome measure was the odds of recurrence of small-for-gestational-age in subsequent pregnancies up to a maximum of 4 consecutive term births.

STUDY DESIGN

This was a retrospective analysis of women who had more than 1 consecutive nonanomalous, singleton, term live births between July 1997 and September 2018 at the Mater Mother's Hospital in Brisbane, Australia. Women with multiple pregnancy, preterm birth, or major congenital malformations were excluded. Small-for-gestational-age was defined as birthweight at the <10th centile. We calculated the odds of recurrence depending on the number of previous small-for-gestational-age infants and if only the preceding infant was small-for-gestational-age. The study population was dichotomized into small-for-gestational-age and non-small-for-gestational-age for each consecutive pregnancy. Univariate analyses compared baseline demographic and obstetrical characteristics followed by logistic regression modeling to determine the odds of recurrence in the second, third, and fourth pregnancies.

RESULTS

The final study comprised 24,819 women. The proportion of women who had a small-for-gestational-age infant in their first pregnancy was 9.4%, whereas the proportion of women who had a small-for-gestational-age infant in their second, third, and fourth pregnancies after the birth of a previous small-for-gestational-age infant were 20.5% (479 of 2338), 24.6% (63 of 256), and 30.4% (14 of 46), respectively. Regardless of parity, the odds of recurrence increased if the preceding infant was small-for-gestational-age. The odds of recurrence increased markedly if there was more than 1 previous small-for-gestational-age infant. In women with 3 previous small-for-gestational-age infants, the adjusted odds of another small-for-gestational-age infant were 66.00 (95% confidence interval, 11.35-383.76). Maternal age, body mass index, ethnicity, and smoking were significant risk factors for recurrent small-for-gestational-age. However, maternal diabetes mellitus or hypertension, either in a previous or current pregnancy, did not influence the risk of recurrence.

CONCLUSION

The risk of recurrence in a subsequent pregnancy increased if there was a previous small-for-gestational-age birth. Women with consecutive small-for-gestational-age infants were at the highest risk of recurrence. Our results highlight that women with a previous small-for-gestational-age infant are at a substantial risk of another small infant and need to be counseled and monitored appropriately.

Prediction of Late-Onset Small for Gestational Age and Fetal Growth Restriction by Fetal Biometry at 35 Weeks and Impact of Ultrasound-Delivery Interval: Comparison of Six Fetal Growth Standards

Small-for-gestational-age (SGA) infants have been associated with increased risk of adverse perinatal outcomes (APOs). In this work, we assess the predictive ability of the ultrasound-estimated percentile weight (EPW) at 35 weeks of gestational age to predict late-onset SGA and APOs, according to six growth standards, and whether the ultrasound–delivery interval influences the detection rate. To this purpose, we analyze a retrospective cohort study of 9585 singleton pregnancies. EPWs at 35 weeks were calculated to the customized Miguel Servet University Hospital (MSUH) and Figueras standards and the non-customized MSUH, Fetal Medicine Foundation (FMF), INTERGROWTH-21st, and WHO standards. As results of our analysis, for a 10% false positive rate, the detection rates for SGA ranged between 48.9% with the customized Figueras standard (AUC 0.82) and 60.8% with the non-customized FMF standard (AUC 0.87). Detection rates to predict SGA by ultrasound–delivery interval (1–6 weeks) show higher detection rates as intervals decrease. APOs detection rates ranged from 27.0% with FMF to 7.9% with the Figueras standard. In conclusion, the ability of EPW to predict SGA at 35 weeks is good for all standards, and slightly better for non-customized standards. The APO detection rate is significantly greater for non-customized standards.

Maternal circulating SPINT1 is reduced in small-for-gestational age pregnancies at 26 weeks: Growing up in Singapore towards health outcomes (GUSTO) cohort study

Fetal growth restriction arising from placental insufficiency is a leading cause of stillbirth. We recently identified low maternal circulating SPINT1 concentrations as a novel biomarker of poor fetal growth. Here we measured SPINT1 in a prospective cohort in Singapore. Circulating SPINT1 concentrations were significantly lower among 141 pregnant women destined to deliver small-for-gestational age infants (birthweight <10th centile), compared to 772 controls (p < 0.01) at as early as 26 weeks' gestation. There were no correlations between infant body composition and circulating SPINT1 concentrations at 26 weeks. This provides validation that low maternal SPINT1 concentration is associated with poor fetal growth.

Routine third-trimester ultrasound for the detection of small-for-gestational age in low-risk pregnancies (ROTTUS study): randomized controlled trial

OBJECTIVE

To compare the proportion of small-for-gestational-age (SGA) infants detected by routine third-trimester ultrasound vs those detected by selective ultrasound based on serial symphysis-fundus height (SFH) measurements (standard care) in low-risk pregnancy.

METHODS

This was an open-label randomized controlled trial conducted at a hospital in Kenya between May 2018 and February 2020. Low-risk pregnant women were randomly allocated (ratio of 1:1) to routine ultrasound for fetal growth assessment between 36 + 0 and 37 + 6 weeks' gestation (intervention group) or to standard care, which involved a selective growth scan on clinical suspicion of fetal growth abnormality based on serial SFH measurements (control group). During ultrasound examination, fetal growth was assessed by measurement of the abdominal circumference (AC), and AC < 10^th centile was used to diagnose a SGA fetus. The main prespecified outcomes were the detection of neonatal SGA, defined as birth weight < 10^th centile, and of severe neonatal SGA, defined as birth weight < 3^rd centile. The predictive performance of routine third-trimester ultrasound and selective ultrasound based on serial SFH measurements was determined using receiver-operating-characteristics (ROC)-curve analysis.

RESULTS

Of 566 women assessed for eligibility, 508 (89.8%) were randomized, of whom 253 were allocated to the intervention group and 255 to the control group. Thirty-six babies in the intervention group and 26 in the control group had a birth weight < 10^th centile. The detection rate of SGA infants by routine third-trimester ultrasound vs that by standard care was 52.8% (19/36) vs 7.7% (2/26) (P < 0.001) and the specificity was 95.5% (191/200) and 97.9% (191/195), respectively (P = 0.08). The detection rate of severe SGA was 66.7% (12/18) by routine ultrasound vs 8.3% (1/12) by selective ultrasound based on SFH measurements (P < 0.001), with specificities of 91.7% (200/218) and 98.1% (205/209), respectively (P = 0.006). The area under the ROC curve of routine third-trimester ultrasound in prediction of SGA was significantly greater than that of selective ultrasound based on SFH measurements (0.92 (95% CI, 0.87-0.96) vs 0.68 (95% CI, 0.58-0.77); P < 0.001).

CONCLUSIONS

In low-risk pregnancy, routine ultrasound performed between 36 + 0 and 37 + 6 weeks is superior to selective ultrasound based on serial SFH measurements for the detection of true SGA, with high specificity. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Placental transverse relaxation time (T2) estimated by MRI: Normal values and the correlation with birthweight

INTRODUCTION

Placental transverse relaxation time (T2) assessed by MRI may have the potential to improve the antenatal identification of small for gestational age. The aims of this study were to provide normal values of placental T2 in relation to gestational age at the time of MRI and to explore the correlation between placental T2 and birthweight.

MATERIAL AND METHODS

A mixed cohort of 112 singleton pregnancies was retrieved from our placental MRI research database. MRI was performed at 23.6-41.3 weeks of gestation in a 1.5T system (TE (8): 50-440 ms, TR: 4000 ms). Normal pregnancies were defined by uncomplicated pregnancies with normal obstetric outcome and birthweight deviation within ±1 SD of the expected for gestational age. The correlation between placental T2 and birthweight was investigated using the following outcomes; small for gestational age (birthweight ≤-2 SD of the expected for gestational age) and birthweight deviation (birthweight Z-scores).

RESULTS

In normal pregnancies (n = 27), placenta T2 showed a significant negative linear correlation with gestational age (r = -.91, P = .0001) being 184 ms ± 15.94 ms (mean ± SD) at 20 weeks of gestation and 89 ms ± 15.94 ms at 40 weeks of gestation. Placental T2 was significantly reduced among small-for-gestational-age pregnancies (mean Z-score -1.95, P < .001). Moreover, we found a significant positive correlation between placenta T2 deviation (Z-score) and birthweight deviation (Z-score) (R²  = .26, P = .0001).

CONCLUSIONS

This study provides normal values of placental T2 to be used in future studies on placental MRI. Placental T2 is closely related to birthweight and may improve the antenatal identification of small-for-gestational-age pregnancies.

Reduced growth velocity from the mid-trimester is associated with placental insufficiency in fetuses born at a normal birthweight

BACKGROUND

Fetal growth restriction (FGR) due to placental insufficiency is a major risk factor for stillbirth. While small-for-gestational-age (SGA; weight < 10th centile) is a commonly used proxy for FGR, detection of FGR among appropriate-for-gestational-age (AGA; weight ≥ 10th centile) fetuses remains an unmet need in clinical care. We aimed to determine whether reduced antenatal growth velocity from the time of routine mid-trimester ultrasound is associated with antenatal, intrapartum and postnatal indicators of placental insufficiency among term AGA infants.

METHODS

Three hundred and five women had biometry measurements recorded from their routine mid-trimester (20-week) ultrasound, at 28 and 36 weeks' gestation, and delivered an AGA infant. Mid-trimester, 28- and 36-week estimated fetal weight (EFW) and abdominal circumference (AC) centiles were calculated. The EFW and AC growth velocities between 20 and 28 weeks, and 20-36 weeks, were examined as predictors of four clinical indicators of placental insufficiency: (i) low 36-week cerebroplacental ratio (CPR; CPR < 5th centile reflects cerebral redistribution-a fetal adaptation to hypoxia), (ii) neonatal acidosis (umbilical artery pH < 7.15) after the hypoxic challenge of labour, (iii) low neonatal body fat percentage (BF%) reflecting reduced nutritional reserve and (iv) placental weight < 10th centile.

RESULTS

Declining 20-36-week fetal growth velocity was associated with all indicators of placental insufficiency. Each one centile reduction in EFW between 20 and 36 weeks increased the odds of cerebral redistribution by 2.5% (odds ratio (OR) = 1.025, P = 0.001), the odds of neonatal acidosis by 2.7% (OR = 1.027, P = 0.002) and the odds of a < 10th centile placenta by 3.0% (OR = 1.030, P < 0.0001). Each one centile reduction in AC between 20 and 36 weeks increased the odds of neonatal acidosis by 3.1% (OR = 1.031, P = 0.0005), the odds of low neonatal BF% by 2.8% (OR = 1.028, P = 0.04) and the odds of placenta < 10th centile by 2.1% (OR = 1.021, P = 0.0004). Falls in EFW or AC of > 30 centiles between 20 and 36 weeks were associated with two-threefold increased relative risks of these indicators of placental insufficiency, while low 20-28-week growth velocities were not.

CONCLUSIONS

Reduced growth velocity between 20 and 36 weeks among AGA fetuses is associated with antenatal, intrapartum and postnatal indicators of placental insufficiency. These fetuses potentially represent an important, under-recognised cohort at increased risk of stillbirth. Encouragingly, this novel fetal assessment would require only one additional ultrasound to current routine care, and adds to the potential benefits of routine 36-week ultrasound.

Prenatal identification of small-for-gestational age and risk of neonatal morbidity and stillbirth

OBJECTIVE

To assess whether prenatal identification of small-for-gestational age (SGA) was associated with lower rates of the primary composite outcome of stillbirth, death in the delivery room or neonatal complications, and secondary outcomes of the composite outcome according to gestational age at delivery, stillbirth and low 5-min Apgar score.

METHODS

This historical cohort study included women who had a singleton delivery (≥ 32 weeks) between 1994 and 2011 at one of 247 French maternity units. We excluded pregnancies terminated medically, infants with malformations or with missing data on estimated fetal weight or birth weight, and women with missing delivery data. Among the 24 946 infants born SGA (< 5^th percentile), we compared those who had been identified as such prenatally (n = 5093; 20%), with those who had not (n = 19 853; 80%). The main outcome was a composite variable defined as stillbirth or death in the delivery room, or transfer to a neonatal department either immediately or during the neonatal stay in the obstetrics ward. Secondary outcomes were the composite outcome according to gestational age at delivery (32 to < 35 weeks; 35 to < 37 weeks, 37 to < 40 weeks, or ≥ 40 weeks), stillbirth and low 5-min Apgar score (≤ 4 and < 7).

RESULTS

The mean ± SD birth weight was 2449.1 ± 368.3 g. The rate of the main composite outcome was higher in the group identified prenatally as SGA compared with non-identified SGA fetuses (39.5% vs 13.5%; adjusted relative risk (aRR), 1.29; 95% CI, 1.21-1.38). This association was not observed in the subgroups delivered before 37 weeks. The stillbirth rate was lower in fetuses with prenatal suspicion of SGA (aRR, 0.47; 95% CI, 0.27-0.79), while the 5-min Apgar score did not differ between the two groups. The a-posteriori study power with α = 0.05 was 99%.

CONCLUSION

Prenatal identification of SGA was not associated with lower fetal or neonatal morbidity overall, although it was associated with a lower rate of stillbirth. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Screening for small-for-gestational-age fetuses

INTRODUCTION

It is well established that correct antenatal identification of small-for-gestational-age (SGA) fetuses reduces their risk of adverse perinatal outcome with long-term consequences. Ultrasound estimates of fetal weight (EFW_us ) are the ultimate tool for this identification. It can be conducted as a "universal screening", that is, all pregnant women at a specific gestational age. However, in Denmark it is conducted as "selective screening", that is, only on clinical indication. The aim of this study was to assess the performance of the Danish national SGA screening program and the consequences of false-positive and false-negative SGA cases.

MATERIAL AND METHODS

In this retrospective cohort study, we included 2928 women with singleton pregnancies with due dates in 2015. We defined "risk of SGA" by an EFW_us  ≤ -15% of expected for the gestational age and "SGA" as birthweight ≤-22% of expected for gestational age.

RESULTS

At birth, the prevalence of SGA was 3.3%. The overall sensitivity of the Danish screening program was 62% at a false-positive rate of 5.6%. Within the entire cohort, 63% had an EFW_us compared with 79% of the SGA cases. The sensitivity was 79% for those born before 37 weeks of gestation but only 40% for those born after 40 weeks of gestation. The sensitivity was also associated with birthweight deviation; 73% among extreme SGA cases (birthweight deviation ≤-33%) and 55% among mild SGA (birthweight deviation between -22% and -27%). False diagnosis of SGA was associated with an increased rate of induction of labor (OR_adj  = 2.51, 95% CI 1.70-3.71) and cesarean section (OR_adj  = 1.44, 95% CI 0.96-2.18).

CONCLUSIONS

The performance of the Danish national screening program for SGA based on selective EFW_us on clinical indication has improved considerably over the last 20 years. Limitations of the program are the large proportion of women referred to ultrasound scan and the low performance post-term.

Prediction of large-for-gestational-age neonate by routine third-trimester ultrasound

OBJECTIVES

First, to evaluate and compare the performance of routine ultrasonographic estimated fetal weight (EFW) and fetal abdominal circumference (AC) at 31 + 0 to 33 + 6 and 35 + 0 to 36 + 6 weeks' gestation in the prediction of a large-for-gestational-age (LGA) neonate born at ≥ 37 weeks' gestation. Second, to assess the additive value of fetal growth velocity between 32 and 36 weeks' gestation to the performance of EFW at 35 + 0 to 36 + 6 weeks' gestation for prediction of a LGA neonate. Third, to define the predictive performance for a LGA neonate of different EFW cut-offs on routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. Fourth, to propose a two-stage strategy for identifying pregnancies with a LGA fetus that may benefit from iatrogenic delivery during the 38^th gestational week.

METHODS

This was a retrospective study. First, data from 21 989 singleton pregnancies that had undergone routine ultrasound examination at 31 + 0 to 33 + 6 weeks' gestation and 45 847 that had undergone routine ultrasound examination at 35 + 0 to 36 + 6 weeks were used to compare the predictive performance of EFW and AC for a LGA neonate with birth weight > 90^th and > 97^th percentiles born at ≥ 37 weeks' gestation. Second, data from 14 497 singleton pregnancies that had undergone routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation and had a previous scan at 30 + 0 to 34 + 6 weeks were used to determine, through multivariable logistic regression analysis, whether addition of growth velocity, defined as the difference in EFW Z-score or AC Z-score between the early and late third-trimester scans divided by the time interval between the scans, improved the performance of EFW at 35 + 0 to 36 + 6 weeks in the prediction of delivery of a LGA neonate at ≥ 37 weeks' gestation. Third, in the database of the 45 847 pregnancies that had undergone routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation, the screen-positive and detection rates for a LGA neonate born at ≥ 37 weeks' gestation and ≤ 10 days after the initial scan were calculated for different EFW percentile cut-offs between the 50^th and 90^th percentiles.

RESULTS

First, the areas under the receiver-operating characteristics curves (AUC) of screening for a LGA neonate were significantly higher using EFW Z-score than AC Z-score and at 35 + 0 to 36 + 6 than at 31 + 0 to 33 + 6 weeks' gestation (P < 0.001 for all). Second, the performance of screening for a LGA neonate achieved by EFW Z-score at 35 + 0 to 36 + 6 weeks was not significantly improved by addition of EFW growth velocity or AC growth velocity. Third, in screening by EFW > 90^th percentile at 35 + 0 to 36 + 6 weeks' gestation, the predictive performance for a LGA neonate born at ≥ 37 weeks' gestation was modest (65% and 46% for neonates with birth weight > 97^th and > 90^th percentiles, respectively, at a screen-positive rate of 10%), but the performance was better for prediction of a LGA neonate born ≤ 10 days after the scan (84% and 71% for neonates with birth weight > 97^th and > 90^th percentiles, respectively, at a screen-positive rate of 11%). Fourth, screening by EFW > 70^th percentile at 35 + 0 to 36 + 6 weeks' gestation predicted 91% and 82% of LGA neonates with birth weight > 97^th and > 90^th percentiles, respectively, born at ≥ 37 weeks' gestation, at a screen-positive rate of 32%, and the respective values of screening by EFW > 85^th percentile for prediction of a LGA neonate born ≤ 10 days after the scan were 88%, 81% and 15%. On the basis of these results, it was proposed that routine fetal biometry at 36 weeks' gestation is a screening rather than diagnostic test for fetal macrosomia and that EFW > 70^th percentile should be used to identify pregnancies in need of another scan at 38 weeks, at which those with EFW > 85^th percentile should be considered for iatrogenic delivery during the 38^th  week.

CONCLUSIONS

First, the predictive performance for a LGA neonate by routine ultrasonographic examination during the third trimester is higher if the scan is carried out at 36 than at 32 weeks, the method of screening is EFW than fetal AC, the outcome measure is birth weight > 97^th than > 90^th percentile and if delivery occurs within 10 days than at any stage after assessment. Second, prediction of a LGA neonate by EFW > 90^th percentile is modest and this study presents a two-stage strategy for maximizing the prenatal prediction of a LGA neonate. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

National-survey for evaluation of the best screening method of late fetal growth restriction in low risk pregnancy: A prospective study

OBJECTIVE

To compare knowledge and practices surrounding third trimester screening of fetal growth restriction (FGR) in low risk pregnancies among Portuguese Gynecologists/Obstetricians (GOs) and General Practitioners (GPs). Primary outcome was to compare the proportion of GOs that consider the need of a third trimester ultrasound (estimation of fetal weight) for screening of FGR in low risk pregnancies and the best time to perform it with the corresponding proportion of GPs.

STUDY DESIGN

We have conducted a prospective, observational cohort study based on application of surveys to GOs and GPs. Questionnaires were sent by e-mail to physicians and they filled them online. A second reminder e-mail was sent 7 days later. Recruitment was also done personally at scientific meetings. A total of 573 surveys were available for analysis, 298 corresponded to GOs and 275 to GPs. We used χ² test to compare dichotomous variables and Kruskal-Wallis test for the comparison of ordinal variables. P values <0.05 were considered statistically significant.

RESULTS

The vast majority of GOs and GPs (93%) considered that third trimester ultrasound is useful and needed for surveillance of low risk pregnancy. A higher proportion of GOs (38%) selected 35th-37th weeks as the best time to perform the ultrasound compared to GPs (10%) (p < 0.001). GOs (51%) consider that symphysis-fundus distance is a measurement with moderate accuracy for screening of FGR while GPs (61%) attribute a low accuracy (p < 0.001). Fifty percent (50%) of GOs consider that performing a third trimester ultrasound will have no impact on cesarean delivery rate for fetal distress, while 41% of GPs consider that routine ultrasound will contribute to increase this rate (p < 0.001). The majority of GPs (52%) consider that routine ultrasound will contribute to diminish the admission rate to neonatal intensive care unit while GOs revealed a dichotomy with 43% of respondents reporting that it will diminish the rate and 40% that it will have no impact.

CONCLUSION

Varied opinions among the clinicians included in our sample reflect the controversy that remains on the best screening of FGR in low risk pregnancies.

Routine ultrasound at 32 vs 36 weeks' gestation: prediction of small-for-gestational-age neonates

OBJECTIVE

To evaluate and compare the performance of routine ultrasonographic estimated fetal weight (EFW) and fetal abdominal circumference (AC) at 31 + 0 to 33 + 6 and 35 + 0 to 36 + 6 weeks' gestation in the prediction of a small-for-gestational-age (SGA) neonate.

METHODS

This was a prospective study of 21 989 singleton pregnancies undergoing routine ultrasound examination at 31 + 0 to 33 + 6 weeks' gestation and 45 847 undergoing routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. In each case, the estimated fetal weight (EFW) from measurements of fetal head circumference, AC and femur length was calculated using the Hadlock formula and expressed as a percentile according to The Fetal Medicine Foundation fetal and neonatal population weight charts. The same charts were used for defining a SGA neonate with birth weight < 10^th and < 3^rd percentiles. For each gestational-age window, the screen-positive and detection rates, at different EFW percentile cut-offs between the 10^th and 50^th percentiles, were calculated for prediction of delivery of a SGA neonate with birth weight < 10^th and < 3^rd percentiles within 2 weeks and at any stage after assessment. The areas under the receiver-operating characteristics curves (AUC) in screening for a SGA neonate by EFW and AC at 31 + 0 to 33 + 6 and at 35 + 0 to 36 + 6 weeks' gestation were compared.

RESULTS

First, the AUCs in screening by EFW for a SGA neonate with birth weight < 10^th and < 3^rd percentiles delivered within 2 weeks and at any stage after screening at 35 + 0 to 36 + 6 weeks' gestation were significantly higher than those at 31 + 0 to 33 + 6 weeks (P < 0.001). Second, at both 35 + 0 to 36 + 6 and 31 + 0 to 33 + 6 weeks' gestation, the predictive performance for a SGA neonate with birth weight < 10^th and < 3^rd percentiles born at any stage after screening was significantly higher using EFW Z-score than AC Z-score. Similarly, at 35 + 0 to 36 + 6 weeks, but not at 31 + 0 to 33 + 6 weeks, the predictive performance for a SGA neonate with birth weight < 10^th and < 3^rd percentiles born within 2 weeks after screening was significantly higher using EFW Z-score than AC Z-score. Third, screening by EFW < 10^th percentile at 35 + 0 to 36 + 6 weeks' gestation predicted 70% and 84% of neonates with birth weight < 10^th and < 3^rd percentiles, respectively, born within 2 weeks after assessment, and the respective values for a neonate born at any stage after assessment were 46% and 65%. Fourth, prediction of > 85% of SGA neonates with birth weight < 10^th percentile born at any stage after screening at 35 + 0 to 36 + 6 weeks' gestation requires use of EFW < 40^th percentile. Screening at this percentile cut-off predicted 95% and 99% of neonates with birth weight < 10^th and < 3^rd percentiles, respectively, born within 2 weeks after assessment, and the respective values for a neonate born at any stage after assessment were 87% and 94%.

CONCLUSIONS

The predictive performance for a SGA neonate of routine ultrasonographic examination during the third trimester is higher if, first, the scan is carried out at 35 + 0 to 36 + 6 weeks' gestation than at 31 + 0 to 33 + 6 weeks, second, the method of screening is EFW than fetal AC, third, the outcome measure is birth weight < 3^rd than < 10^th percentile, and, fourth, if delivery occurs within 2 weeks than at any stage after assessment. Prediction of a SGA neonate by EFW < 10^th percentile is modest and prediction of > 85% of cases at 35 + 0 to 36 + 6 weeks' gestation necessitates use of EFW < 40^th percentile. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Diagnostic performance of third-trimester ultrasound for the prediction of late-onset fetal growth restriction: a systematic review and meta-analysis

OBJECTIVE

The objective of the study was to establish the diagnostic performance of ultrasound screening for predicting late smallness for gestational age and/or fetal growth restriction.

DATA SOURCES

A systematic search was performed to identify relevant studies published since 2007 in English, Spanish, French, Italian, or German, using the databases PubMed, ISI Web of Science, and SCOPUS.

STUDY ELIGIBILITY CRITERIA

We used rrospective and retrospective cohort studies in low-risk or nonselected singleton pregnancies with screening ultrasound performed at ≥32 weeks of gestation.

STUDY APPRAISAL AND SYNTHESIS METHODS

The estimated fetal weight and fetal abdominal circumference were assessed as index tests for the prediction of birthweight <10th (i.e. smallness for gestational age), less than the fifth, and less than the third centile and fetal growth restriction (estimated fetal weight less than the third or estimated fetal weight <10th plus Doppler signs). Quality of the included studies was independently assessed by 2 reviewers, using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. For the meta-analysis, hierarchical summary receiver-operating characteristic curves were constructed, and quantitative data synthesis was performed using random-effects models. The sensitivity of the abdominal circumference <10th centile and estimated fetal weight <10th centile for a fixed 10% false-positive rate was derived from the corresponding hierarchical summary receiver-operating characteristic curves. Heterogeneity between studies was visually assessed using Galbraith plots, and publication bias was assessed by funnel plots and quantified by Deeks' method.

RESULTS

A total of 21 studies were included. Observed pooled sensitivities of abdominal circumference and estimated fetal weight <10th centile for birthweight <10th centile were 35% (95% confidence interval, 20-52%) and 38% (95% confidence interval, 31-46%), respectively. Observed pooled specificities were 97% (95% confidence interval, 95-98%) and 95% (95% confidence interval, 93-97%), respectively. Modeled sensitivities of abdominal circumference and estimated fetal weight <10th centile for 10% false-positive rate were 78% (95% confidence interval, 61-95%) and 54% (95% confidence interval, 46-52%), respectively. The sensitivity of estimated fetal weight <10th centile was better when aimed to fetal growth restriction than to smallness for gestational age. Meta-regression analysis showed a significant increase in sensitivity when ultrasound evaluation was performed later in pregnancy (P = .001).

CONCLUSION

Third-trimester abdominal circumference and estimated fetal weight perform similar in predicting smallness for gestational age. However, for a fixed 10% false-positive rate extrapolated sensitivity is higher for abdominal circumference. There is evidence of better performance when the scan is performed near term and when fetal growth restriction is the targeted condition.

Prediction of small-for-gestational-age neonates at 35-37 weeks' gestation: contribution of maternal factors and growth velocity between 32 and 36 weeks

OBJECTIVE

To assess the additive value of fetal growth velocity between 32 and 36 weeks' gestation to the performance of ultrasonographic estimated fetal weight (EFW) at 35 + 0 to 36 + 6 weeks' gestation for prediction of delivery of a small-for-gestational-age (SGA) neonate and adverse perinatal outcome.

METHODS

This was a prospective study of 14 497 singleton pregnancies undergoing routine ultrasound examination at 30 + 0 to 34 + 6 and at 35 + 0 to 36 + 6 weeks' gestation. Multivariable logistic regression analysis was used to determine whether addition of growth velocity, defined as the difference in EFW Z-score or abdominal circumference (AC) Z-score between the early and late third-trimester scans divided by the time interval between the scans, improved the performance of EFW Z-score at 35 + 0 to 36 + 6 weeks in the prediction of, first, delivery of a SGA neonate with birth weight < 10^th and < 3^rd percentiles within 2 weeks and at any stage after assessment and, second, a composite of adverse perinatal outcome, defined as stillbirth, neonatal death or admission to the neonatal unit for ≥ 48 h.

RESULTS

Multivariable logistic regression analysis demonstrated that significant contributors to the prediction of a SGA neonate were EFW Z-score at 35 + 0 to 36 + 6 weeks' gestation, fetal growth velocity, by either AC Z-score or EFW Z-score, and maternal risk factors. The area under the receiver-operating characteristics curve (AUC) and detection rate (DR), at a 10% screen-positive rate, for prediction of a SGA neonate < 10^th percentile born within 2 weeks after assessment achieved by EFW Z-score at 35 + 0 to 36 + 6 weeks (AUC, 0.938 (95% CI, 0.928-0.947); DR, 80.7% (95% CI, 77.6-83.9%)) were not significantly improved by addition of EFW growth velocity and maternal risk factors (AUC, 0.941 (95% CI, 0.932-0.950); P = 0.061; DR, 82.5% (95% CI, 79.4-85.3%)). Similar results were obtained when growth velocity was defined by AC rather than EFW. Similarly, there was no significant improvement in the AUC and DR, at a 10% screen-positive rate, for prediction of a SGA neonate < 10^th percentile born at any stage after assessment or a SGA neonate < 3^rd percentile born within 2 weeks or at any stage after assessment, achieved by EFW Z-score at 35 + 0 to 36 + 6 weeks by addition of maternal factors and either EFW growth velocity or AC growth velocity. Multivariable logistic regression analysis demonstrated that the only significant contributor to adverse perinatal outcome was maternal risk factors. Multivariable logistic regression analysis in the group with EFW < 10^th percentile demonstrated that significant contribution to prediction of delivery of a neonate with birth weight < 10^th and < 3^rd percentiles and adverse perinatal outcome was provided by EFW Z-score at 35 + 0 to 36 + 6 weeks, but not by AC growth velocity < 1^st decile.

CONCLUSION

The predictive performance of EFW at 35 + 0 to 36 + 6 weeks' gestation for delivery of a SGA neonate and adverse perinatal outcome is not improved by addition of estimated growth velocity between 32 and 36 weeks' gestation. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Prediction of small for gestational age neonates: screening by maternal factors, fetal biometry, and biomarkers at 35-37 weeks' gestation

BACKGROUND

Small for gestational age (SGA) neonates are at increased risk for perinatal mortality and morbidity; however, the risks can be substantially reduced if the condition is identified prenatally, because in such cases close monitoring and appropriate timing of delivery and prompt neonatal care can be undertaken. The traditional approach of identifying pregnancies with SGA fetuses is maternal abdominal palpation and serial measurements of symphysial-fundal height, but the detection rate of this approach is less than 30%. A higher performance of screening for SGA is achieved by sonographic fetal biometry during the third trimester; screening at 30-34 weeks' gestation identifies about 80% of SGA neonates delivering preterm but only 50% of those delivering at term, at a screen-positive rate of 10%. There is some evidence that routine ultrasound examination at 36 weeks' gestation is more effective than that at 32 weeks in predicting birth of SGA neonates.

OBJECTIVE

To investigate the potential value of maternal characteristics and medical history, sonographically estimated fetal weight (EFW) and biomarkers of impaired placentation at 35⁺⁰- 36⁺⁶ weeks' gestation in the prediction of delivery of SGA neonates.

MATERIALS AND METHODS

A dataset of 19,209 singleton pregnancies undergoing screening at 35⁺⁰-36⁺⁶ weeks' gestation was divided into a training set and a validation set. The training dataset was used to develop models from multivariable logistic regression analysis to determine whether the addition of uterine artery pulsatility index (UtA-PI), umbilical artery PI (UA-PI), fetal middle cerebral artery PI (MCA-PI), maternal serum placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFLT) would improve the performance of maternal factors and EFW in the prediction of delivery of SGA neonates. The models were then tested in the validation dataset to assess performance of screening.

RESULTS

First, in the training dataset, in the SGA group, compared to those with birthweight in ≥10th percentile, the median multiple of the median (MoM) values of PlGF and MCA-PI were reduced, whereas UtA-PI, UA-PI, and sFLT were increased. Second, multivariable regression analysis demonstrated that in the prediction of SGA in <10th percentile there were significant contributions from maternal factors, EFW Z-score, UtA-PI MoM, MCA-PI MoM, and PlGF MoM. Third, in the validation dataset, prediction of 90% of SGA neonates delivering within 2 weeks of assessment was achieved by a screen-positive rate of 67% (95% confidence interval [CI], 64-70%) in screening by maternal factors, 23% (95% CI, 20-26%) by maternal factors, and EFW and 21% (95% CI, 19-24%) by the addition of biomarkers. Fourth, prediction of 90% of SGA neonates delivering at any stage after assessment was achieved by a screen-positive rate of 66% (95% CI, 65-67%) in screening by maternal factors, 32% (95% CI, 31-33%) by maternal factors and EFW and 30% (95% CI, 29-31%) by the addition of biomarkers.

CONCLUSION

The addition of biomarkers of impaired placentation only marginally improves the predictive performance for delivery of SGA neonates achieved by maternal factors and fetal biometry at 35⁺⁰-36⁺⁶ weeks' gestation.

Fetal Medicine Foundation reference ranges for umbilical artery and middle cerebral artery pulsatility index and cerebroplacental ratio

OBJECTIVES

To develop gestational age-based reference ranges for the pulsatility index in the umbilical artery (UA-PI) and fetal middle cerebral artery (MCA-PI) and the cerebroplacental ratio (MCA-PI/UA-PI), and to examine the maternal characteristics and medical history that affect these measurements.

METHODS

This was a cross-sectional study of 72 387 pregnancies undergoing routine ultrasound examination at 20 + 0 to 22 + 6 weeks' gestation (n = 3712), 31 + 0 to 33 + 6 weeks (n = 29 035), 35 + 0 to 36 + 6 weeks (n = 37 252) or 41 + 0 to 41 + 6 weeks (n = 2388). For the purpose of this study, we included data for only one of the second- or third-trimester visits. The inclusion criteria were singleton pregnancy, dating by fetal crown-rump length at 11 + 0 to 13 + 6 weeks' gestation, live birth of a morphologically normal neonate and ultrasonographic measurements by sonographers who had received the Fetal Medicine Foundation Certificate of Competence in Doppler ultrasound. Since the objectives of the study were to establish reference ranges, rather than normal ranges, and to examine factors from maternal characteristics and medical history that affect these measurements, we included all pregnancies having routine ultrasound examinations, irrespective of whether the mother had a pre-existing medical condition, such as diabetes mellitus, or a pregnancy complication, such as pre-eclampsia or suspected fetal growth restriction. Median and SD models were fitted between UA-PI, MCA-PI and CPR and gestational age. Assessment of goodness of fit of the models was by inspection of quantile-to-quantile (Q-Q) plots of Z-scores calculated using the mean and SD models. The distributions of MCA-PI, UA-PI and CPR Z-scores were examined in relation to maternal characteristics and medical history.

RESULTS

The relationship between the median and gestational age was linear for UA-PI and cubic for MCA-PI and CPR and the SD was log quadratic for all three. MCA-PI and CPR increased with gestational age from 20 weeks' gestation to reach a peak at around 32 and 34 weeks, respectively, and decreased thereafter, whereas UA-PI decreased linearly with gestational age from 20 to 42 weeks. Compared to the general population, significant deviations in multiples of the median values of UA-PI, MCA-PI and CPR were observed in subgroups of maternal age, body mass index, racial origin, method of conception and parity.

CONCLUSION

This study established new reference ranges for UA-PI, MCA-PI and CPR, according to gestational age, and reports maternal characteristics and medical history that affect these measurements. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Prediction of small-for-gestational-age neonates at 35-37 weeks' gestation: contribution of maternal factors and growth velocity between 20 and 36 weeks

OBJECTIVES

To evaluate the performance of ultrasonographic estimated fetal weight (EFW) at 35 + 0 to 36 + 6 weeks' gestation in the prediction of delivery of a small-for-gestational-age (SGA) neonate and assess the additive value of, first, maternal risk factors and, second, fetal growth velocity between 20 and 36 weeks' gestation in improving such prediction.

METHODS

This was a prospective study of 44 043 singleton pregnancies undergoing routine ultrasound examination at 19 + 0 to 23 + 6 and at 35 + 0 to 36 + 6 weeks' gestation. Multivariable logistic regression analysis was used to determine whether addition of maternal risk factors and growth velocity, the latter defined as the difference in EFW Z-score or fetal abdominal circumference (AC) Z-score between the third- and second-trimester scans divided by the time interval between the scans, improved the performance of EFW Z-score at 35 + 0 to 36 + 6 weeks in the prediction of delivery of a SGA neonate with birth weight < 10^th and < 3^rd percentiles within 2 weeks and at any stage after assessment.

RESULTS

Screening by EFW Z-score at 35 + 0 to 36 + 6 weeks' gestation predicted 63.4% (95% CI, 62.0-64.7%) of neonates with birth weight < 10^th percentile and 74.2% (95% CI, 72.2-76.1%) of neonates with birth weight < 3^rd percentile born at any stage after assessment, at a screen-positive rate of 10%. The respective values for SGA neonates born within 2 weeks after assessment were 76.8% (95% CI, 74.4-79.0%) and 81.3% (95% CI, 78.2-84.0%). For a desired 90% detection rate of SGA neonate delivered at any stage after assessment, the necessary screen-positive rate would be 33.7% for SGA < 10^th percentile and 24.4% for SGA < 3^rd percentile. Multivariable logistic regression analysis demonstrated that, in the prediction of a SGA neonate with birth weight < 10^th and < 3^rd percentiles, there was a significant contribution from EFW Z-score at 35 + 0 to 36 + 6 weeks' gestation, maternal risk factors and AC growth velocity, but not EFW growth velocity. However, the area under the receiver-operating characteristics curve for prediction of delivery of a SGA neonate by screening with maternal risk factors and EFW Z-score was not improved by addition of AC growth velocity.

CONCLUSION

Screening for SGA neonates by EFW at 35 + 0 to 36 + 6 weeks' gestation and use of the 10^th percentile as the cut-off predicts 63% of affected neonates. Prediction of 90% of SGA neonates necessitates classification of about 35% of the population as being screen positive. The predictive performance of EFW is not improved by addition of estimated growth velocity between the second and third trimesters of pregnancy. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Screening for pre-eclampsia at 35-37 weeks' gestation

OBJECTIVE

To examine the performance of screening for pre-eclampsia (PE) at 35-37 weeks' gestation by maternal factors and combinations of mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), serum placental growth factor (PlGF) and serum soluble fms-like tyrosine kinase-1 (sFlt-1).

METHODS

This was a prospective observational study in women with singleton pregnancy attending for an ultrasound scan at 35 + 0 to 36 + 6 weeks as part of routine pregnancy care. Bayes' theorem was used to combine the prior distribution of gestational age at delivery with PE, obtained from maternal characteristics and medical history, with various combinations of biomarker multiples of the median (MoM) values to derive the patient-specific risks of delivery with PE. The performance of such screening was estimated.

RESULTS

The study population of 13 350 pregnancies included 272 (2.0%) that subsequently developed PE. In pregnancies that developed PE, the MoM values of MAP, UtA-PI and sFlt-1 were increased and PlGF MoM was decreased. At a risk cut-off of 1 in 20, the proportion of the population stratified into high risk was about 10% of the total, and the proportion of cases of PE contained within this high-risk group was 28% with screening by maternal factors alone; the detection rate increased to 53% with the addition of MAP, 67% with the addition of MAP and PlGF and 70% with the addition of MAP, PlGF and sFlt-1. The performance of screening was not improved by the addition of UtA-PI. The performance of screening depended on the racial origin of the women; in screening by a combination of maternal factors, MAP, PlGF and sFlt-1 and use of the risk cut-off of 1 in 20, the detection rate and screen-positive rate were 66% and 9.5%, respectively, for Caucasian women and 88% and 18% for those of Afro-Caribbean racial origin.

CONCLUSION

Screening by maternal factors and biomarkers at 35-37 weeks' gestation can identify a high proportion of pregnancies that develop late PE. The performance of screening depends on the racial origin of the women. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

The Role of Extremes in Interpregnancy Interval in Women at Increased Risk for Adverse Obstetric Outcomes Due to Health Disparities: A Literature Review

Background:

The interpregnancy interval (IPI) defines the time between two consecutive gestations. In the general population, women with IPIs that fall outside the recommended 18-24 month range appear to be at modestly increased risk for adverse obstetric outcomes.

Objective:

The aim of this review was to assess the impact of extremes in IPI in populations with an increased baseline risk for adverse obstetric outcomes due to disparities in health and health care, including racial and ethnic groups, adolescents, and those of lower socioeconomic status.

Methods:

We conducted a MEDLINE/Pubmed literature search in February 2016. Identified articles were reviewed and assigned a level of evidence.

Results:

The 24 studies included in our final review were mainly retrospective with considerable heterogeneity in definitions and outcomes that prevented a quantitative meta-analysis.

Conclusion:

The results of our review suggest that at-risk populations may have an increased frequency of shortened IPIs though the impact appears to be moderate and inconsistent. There was insufficient evidence to draw meaningful conclusions regarding a prolonged IPI or the effect of interventions. Based on the current literature, under-served populations are more likely to have a shortened IPI which increased the incidence of prematurity and low birth weight in some groups though the effect on additional obstetric outcomes is difficult to assess

Prediction and prevention of small-for-gestational-age neonates: evidence from SPREE and ASPRE

OBJECTIVES

To examine the effect of first-trimester screening for pre-eclampsia (PE) on the prediction of delivering a small-for-gestational-age (SGA) neonate and the effect of prophylactic use of aspirin on the prevention of SGA.

METHODS

The data for this study were derived from two multicenter studies. In SPREE, we investigated the performance of screening for PE by a combination of maternal characteristics and biomarkers at 11-13 weeks' gestation. In ASPRE, women with a singleton pregnancy identified by combined screening as being at high risk for preterm PE (> 1 in 100) participated in a trial of aspirin (150 mg/day from 11-14 until 36 weeks' gestation) compared to placebo. In this study, we used the data from the ASPRE trial to estimate the effect of aspirin on the incidence of SGA with birth weight < 10^th , < 5^th and < 3^rd percentile for gestational age. We also used the data from SPREE to estimate the proportion of SGA in the pregnancies with a risk for preterm PE of > 1 in 100.

RESULTS

In SPREE, screening for preterm PE by a combination of maternal factors, mean arterial pressure, uterine artery pulsatility index and serum placental growth factor identified a high-risk group that contained about 46% of SGA neonates < 10^th percentile born at < 37 weeks' gestation (preterm) and 56% of those born at < 32 weeks (early); the overall screen-positive rate was 12.2% (2014 of 16 451 pregnancies). In the ASPRE trial, use of aspirin reduced the overall incidence of SGA < 10^th percentile by about 40% in babies born at < 37 weeks' gestation and by about 70% in babies born at < 32 weeks; in babies born at ≥ 37 weeks, aspirin did not have a significant effect on incidence of SGA. The aspirin-related decrease in incidence of SGA was mainly due to its incidence decreasing in pregnancies with PE, for which the decrease was about 70% in babies born at < 37 weeks' gestation and about 90% in babies born at < 32 weeks. On the basis of these results, it was estimated that first-trimester screening for preterm PE and use of aspirin in the high-risk group would potentially reduce the incidence of preterm and early SGA by about 20% and 40%, respectively.

CONCLUSION

First-trimester screening for PE by the combined test identifies a high proportion of cases of preterm SGA that can be prevented by the prophylactic use of aspirin. © 2018 Crown copyright. Ultrasound in Obstetrics & Gynecology © 2018 ISUOG.

Term small-for-gestational-age infants from low-risk women are at significantly greater risk of adverse neonatal outcomes

BACKGROUND

Small-for-gestational-age infants (birthweight <0th centile) are at increased risk of perinatal complications but are frequently not identified antenatally, particularly in low-risk women delivering at term (≥37 weeks gestation). This is compounded by the fact that late pregnancy ultrasound is not the norm in many jurisdictions for this cohort of women. We thus investigated the relationship between birthweight <10th centile and serious neonatal outcomes in low-risk women at term.

OBJECTIVE(S)

We aimed to determine whether there is a difference of obstetric and perinatal outcomes for small-for-gestational-age infants, subdivided into fifth to <10th centile and less than the fifth centile cohorts compared with an appropriate-for-gestational age (birthweight 10th-90th centile) group at term.

STUDY DESIGN

This was a retrospective analysis of data from the Mater Mother's Hospital in Brisbane, Australia, for women who delivered between January 2000 and December 2015. Women with multiple pregnancy, diabetes mellitus, hypertension, preterm birth, major congenital anomalies, and large for gestational age infants (>90th centile for gestational age) were excluded. Small-for-gestational-age infants were subdivided into 2 cohorts: infants with birthweights from the fifth to <10th centile and those less than the fifth centile. Serious composite neonatal morbidity was defined as any of the following: Apgar score ≤3 at 5 minutes, respiratory distress syndrome, acidosis, admission into the neonatal intensive care unit, stillbirth, or neonatal death. Univariate and multivariate analyses were performed using generalized estimating equations to compare obstetric and perinatal outcomes for small-for-gestational-age infants compared with appropriate-for-gestational age controls.

RESULTS

The final study comprised 95,900 infants. Five percent were between the fifth and <10th centiles for birthweight and 4.3% were less than the fifth centile. The rate of serious composite neonatal morbidity was 11.1% in the control group, 13.7% in the fifth and <10th centile, and 22.6% in the less than the fifth centile cohorts, respectively. Even after controlling for confounders, both the fifth to <10th centiles and less than the fifth centile cohorts were at significantly increased risk of serious composite neonatal morbidity compared with controls (odds ratio, 1.25, 95% confidence interval, 1.15-1.37, and odds ratio, 2.20, 95% confidence interval, 2.03-2.39, respectively). Infants with birthweights <10th centile were more likely to have severe acidosis at birth, 5 minute Apgar score ≤3 and to be admitted to the neonatal intensive care unit. The serious composite neonatal morbidity was higher in infants less than the fifth centile compared with those in the fifth to <10th centile cohort (odds ratio, 1.71, 95% confidence interval, 1.52-1.92). The odds of perinatal death (stillbirth and neonatal death) were significantly higher in both small-for-gestational age groups than controls. After stratification for gestational age at birth, the composite outcome remained significantly higher in both small-for-gestational-age cohorts and was highest in the less than the fifth centile group at 37+0 to 38+6 weeks (odds ratio, 3.32, 95% confidence interval, 2.87-3.85). The risk of perinatal death was highest for infants less than the fifth centile at 37+0 to 38+6 weeks (odds ratio, 5.50, 95% confidence interval, 2.33-12.98).

CONCLUSION

Small-for-gestational-age infants from term, low-risk pregnancies are at significantly increased risk of mortality and morbidity when compared with appropriate-for-gestational age infants. Although this risk is increased at all gestational ages in infants less than the fifth centile for birthweight, it is highest at early-term gestation. Our findings highlight that early-term birth does not necessarily improve outcomes and emphasize the importance of identifying this cohort of infants.

Identifying Fetal Growth Disorders Using Ultrasonography in Women With Diabetes

OBJECTIVES

We evaluated the ability of third-trimester ultrasonography (US) to diagnose disorders of fetal growth among women with diabetes mellitus.

METHODS

This work was a retrospective cohort study of women with diabetes who delivered term singleton neonates at a single academic medical center and who had a US examination within 5 weeks of delivery. We characterized the sensitivity, specificity, positive predictive value, and negative predictive value of US to detect large-for-gestational age (LGA) and small-for-gestational age (SGA) infants. Large and small for gestational age were defined as a US estimated fetal weight of greater than 90% and less than 10%, respectively, based on the Hadlock formula (Radiology 1991; 181:129-133); US estimates of LGA or SGA were compared with postnatal findings of LGA or SGA based on gestational age-based weight percentiles. Test characteristics were analyzed for the total cohort and by the type of diabetes. We compared the areas under the curve for receiver operating characteristic curves for different types of diabetes.

RESULTS

Of 521 women, 3 (0.6%) screened positive for SGA, and 64 (12.3%) delivered an SGA neonate. In contrast, 129 (24.8%) screened positive for LGA, and 61 (11.7%) delivered an LGA neonate. The receiver operating characteristic curves did not differ significantly for different types of diabetes (P = .68).

CONCLUSIONS

Ultrasonography in women with diabetes and term or late preterm pregnancies has high specificity but poor sensitivity for SGA and a low positive predictive value for LGA. The diagnostic capability of US to detect fetal growth abnormalities did not differ significantly by the type of diabetes.

Diagnosis and surveillance of late-onset fetal growth restriction

By consensus, late fetal growth restriction is that diagnosed >32 weeks. This condition is mildly associated with a higher risk of perinatal hypoxic events and suboptimal neurodevelopment. Histologically, it is characterized by the presence of uteroplacental vascular lesions (especially infarcts), although the incidence of such lesions is lower than in preterm fetal growth restriction. Screening procedures for fetal growth restriction need to identify small babies and then differentiate between those who are healthy and those who are pathologically small. First- or second-trimester screening strategies provide detection rates for late smallness for gestational age <50% for 10% of false positives. Compared to clinically indicated ultrasonography in the third trimester, universal screening triples the detection rate of late smallness for gestational age. As opposed to early third-trimester ultrasound, scanning late in pregnancy (around 37 weeks) increases the detection rate for birthweight <3rd centile. Contrary to early fetal growth restriction, umbilical artery Doppler velocimetry alone does not provide good differentiation between late smallness for gestational age and fetal growth restriction. A combination of biometric parameters (with severe smallness usually defined as estimated fetal weight or abdominal circumference <3rd centile) with Doppler criteria of placental insufficiency (either in the maternal [uterine Doppler] or fetal [cerebroplacental ratio] compartments) offers a classification tool that correlates with the risk for adverse perinatal outcome. There is no evidence that induction of late fetal growth restriction at term improves perinatal outcomes nor is it a cost-effective strategy, and it may increase neonatal admission when performed <38 weeks.

Prediction of fetal growth restriction using estimated fetal weight vs a combined screening model in the third trimester

OBJECTIVES

To compare the performance of third-trimester screening, based on estimated fetal weight centile (EFWc) vs a combined model including maternal baseline characteristics, fetoplacental ultrasound and maternal biochemical markers, for the prediction of small-for-gestational-age (SGA) neonates and late-onset fetal growth restriction (FGR).

METHODS

This was a nested case-control study within a prospective cohort of 1590 singleton gestations undergoing third-trimester (32 + 0 to 36 + 6 weeks' gestation) evaluation. Maternal baseline characteristics, mean arterial pressure, fetoplacental ultrasound and circulating biochemical markers (placental growth factor (PlGF), lipocalin-2, unconjugated estriol and inhibin A) were assessed in all women who subsequently delivered a SGA neonate (n = 175), defined as birth weight < 10^th centile according to customized standards, and in a control group (n = 875). Among SGA cases, those with birth weight < 3^rd centile and/or abnormal uterine artery pulsatility index (UtA-PI) and/or abnormal cerebroplacental ratio (CPR) were classified as FGR. Logistic regression predictive models were developed for SGA and FGR, and their performance was compared with that obtained using EFWc alone.

RESULTS

In SGA cases, EFWc, CPR Z-score and maternal serum concentrations of unconjugated estriol and PlGF were significantly lower, while mean UtA-PI Z-score and lipocalin-2 and inhibin A concentrations were significantly higher, compared with controls. Using EFWc alone, 52% (area under receiver-operating characteristics curve (AUC), 0.82 (95% CI, 0.77-0.85)) of SGA and 64% (AUC, 0.86 (95% CI, 0.81-0.91)) of FGR cases were predicted at a 10% false-positive rate. A combined screening model including a-priori risk (maternal characteristics), EFWc, UtA-PI, PlGF and estriol (with lipocalin-2 for SGA) achieved a detection rate of 61% (AUC, 0.86 (95% CI, 0.83-0.89)) for SGA cases and 77% (AUC, 0.92 (95% CI, 0.88-0.95)) for FGR. The combined model for the prediction of SGA and FGR performed significantly better than did using EFWc alone (P < 0.001 and P = 0.002, respectively).

CONCLUSIONS

A multivariable integrative model of maternal characteristics, fetoplacental ultrasound and maternal biochemical markers modestly improved the detection of SGA and FGR cases at 32-36 weeks' gestation when compared with screening based on EFWc alone. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Fractional fetal thigh volume in the prediction of normal and abnormal fetal growth during the third trimester of pregnancy

Background

Currently, 2-dimensional ultrasound estimation of fetal size rather than fetal growth is used to define fetal growth restriction, but single estimates in late pregnancy lack sensitivity and may identify small for gestational age rather than growth restriction. Single or longitudinal measures of 3-dimensional fractional thigh volume may address this problem.

Objective

We sought to derive normal values for 3-dimensional fractional thigh volume in the third trimester, determine if fractional thigh volume is superior to 2-dimensional ultrasound biometry alone for detecting fetal growth restriction, and determine whether individualized growth assessment parameters have the potential to identify fetal growth restriction remote from term delivery.

Study Design

This was a longitudinal prospective cohort study of 115 unselected pregnancies in a tertiary referral unit (St Mary’s Hospital, Manchester, United Kingdom). Standard 2-dimensional ultrasound biometry measurements were obtained, along with fractional thigh volume measurements (based on 50% of the femoral diaphysis length). Measurements were used to calculate estimated fetal weight (Hadlock). Individualized growth assessment parameters and percentage deviations in longitudinally measured biometrics were determined using a Web-based system (iGAP; http://iGAP.research.bcm.edu). Small for gestational age was defined <10th and fetal growth restriction <3rd customized birthweight centile. Logistic regression was used to compare estimated fetal weight (Hadlock), estimated fetal weight (biparietal diameter–abdominal circumference–fractional thigh volume), fractional thigh volume, and abdominal circumference for the prediction of small for gestational age or fetal growth restriction at birth. Screening performance was assessed using area under the receiver operating characteristic curve.

Results

There was a better correlation between fractional thigh volume and estimated fetal weight ((biparietal diameter–abdominal circumference–fractional thigh volume) obtained at 34-36 weeks with birthweight than between 2-dimensional biometry measures such as abdominal circumference and estimated fetal weight (Hadlock). There was also a modest improvement in the detection of both small for gestational age and fetal growth restriction using fractional thigh volume–derived measures compared to standard 2-dimensional measurements (area under receiver operating characteristic curve, 0.86; 95% confidence interval, 0.79–0.94, and area under receiver operating characteristic curve, 0.92; 95% confidence interval, 0.85–0.99, respectively).

Conclusion

Fractional thigh volume measurements offer some improvement over 2-dimensional biometry for the detection of late-onset fetal growth restriction at 34-36 weeks.

Computing the Z Score and Centiles for Cross-sectional Analysis: A Practical Approach

Although Z scores have been reported in the literature, one of the problems for the nonstatistician is understanding the systematic approach used to compute the predicted mean and standard deviation, components of the Z score equation, which may vary as the independent variable changes over time (eg, gestational age). This review focuses on a step-by-step analysis using linear, quadratic, and fractional polynomials to compute the mean and standard deviation as a function of a continuous independent variable. Once the mean and standard deviation are computed, the Z score and centile can be derived and Z score calculators created that enable investigators to implement the results in the laboratory and/or clinical setting.

Prediction of small-for-gestational-age neonate by third-trimester fetal biometry and impact of ultrasound-delivery interval

OBJECTIVES

To compare third-trimester ultrasound screening methods to predict small-for-gestational age (SGA), and to evaluate the impact of the ultrasound-delivery interval on screening performance.

METHODS

In this prospective study, data were collected from a multicenter singleton cohort study investigating the links between various exposures during pregnancy with birth outcome and later health in children. We included women, recruited in the first trimester, who had complete outcome data and had undergone third-trimester ultrasound examination. Demographic, clinical and biological variables were also collected from both parents. We compared prediction of delivery of a SGA neonate (birth weight < 10^th percentile) by the following methods: abdominal circumference (AC) Z-score based on Hadlock curves (Hadlock AC), on INTERGROWTH-21^st Project curves (Intergrowth AC) and on Salomon curves (Salomon AC); estimated fetal weight (EFW) Z-score based on Hadlock curves (Hadlock EFW) and on customized curves from Gardosi (Gardosi EFW); and fetal growth velocity based on change in AC between second and third trimesters (FGVAC). We also assessed the following ultrasound-delivery intervals: ≤ 4 weeks, ≤ 6 weeks and ≤ 10 weeks.

RESULTS

Third-trimester ultrasound was performed in 1805 patients with complete outcome data, of whom 158 (8.8%) delivered a SGA neonate. Ultrasound examination was at a median gestational age of 32 (interquartile range, 31-33) weeks. The ultrasound-delivery interval was ≤ 4 weeks in 17.2% of cases, ≤ 6 weeks in 48.1% of cases and ≤ 10 weeks in 97.3% of cases. Areas under the receiver-operating characteristics curve (AUC) were 0.772 for Salomon AC, 0.768 for Hadlock EFW, 0.766 for Hadlock AC, 0.765 for Intergrowth AC, 0.708 for Gardosi EFW and 0.674 for FGVAC (all P < 0.0001). The screening method with the highest AUC for an ultrasound-delivery interval ≤ 4 weeks was Salomon AC (AUC, 0.856), ≤ 6 weeks was Hadlock AC (AUC, 0.824) and ≤ 10 weeks was Salomon AC (AUC, 0.780). At a fixed 10% false-positive rate, the best detection rates were 60.0%, 54.1% and 42.1% for intervals ≤ 4, ≤ 6 and ≤ 10 weeks, respectively.

CONCLUSION

Third-trimester ultrasound measurements provide poor to moderate prediction of SGA. A shorter ultrasound-delivery interval provides better prediction than does a longer interval. Further studies are needed to test the effect of including maternal or biological characteristics in SGA screening. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

RELATIONSHIP BETWEEN CLINICAL, PLACENTARY, OBSTETRIC AND NEONATAL ASPECTS AND INTRAUTERINE GROWTH IN HIGH RISK PREGNANCIES

ABSTRACT Objective: to analyze clinical, placental and obstetric aspects of women with and without high-risk pregnancy, and their relationship with intrauterine growth deviations and neonatal aspects. Method: this is a cross-sectional descriptive study. Data collection was based on an analysis of the medical records of women with and without high-risk pregnancy and newborns, and anatomopathological characterization of the placenta. Results: 265 placentas were analyzed, 130 (49.06%) women with high-risk pregnancy and newborns with intrauterine growth deviations. A higher occurrence of placental changes was found in high-risk pregnancy and uterine growth deviations in comparison to cases without high-risk pregnancy (p≤0.001). High-risk pregnancies with intrauterine growth deviations were associated with placental changes (p≤0.001). Intrauterine growth deviations was related to birth weight in cases of high-risk pregnancy compared to normal gestation (p=0.014). Conclusion: a higher occurrence of placental anatomopathological changes was found in maternal and fetal surfaces in cases of high-risk pregnancy and intrauterine growth deviations.

Single and Serial Fetal Biometry to Detect Preterm and Term Small- and Large-for-Gestational-Age Neonates: A Longitudinal Cohort Study

Objectives

To assess the value of single and serial fetal biometry for the prediction of small- (SGA) and large-for-gestational-age (LGA) neonates delivered preterm or at term.

Methods

A cohort study of 3,971 women with singleton pregnancies was conducted from the first trimester until delivery with 3,440 pregnancies (17,334 scans) meeting the following inclusion criteria: 1) delivery of a live neonate after 33 gestational weeks and 2) two or more ultrasound examinations with fetal biometry parameters obtained at ≤36 weeks. Primary outcomes were SGA (<5^th centile) and LGA (>95^th centile) at birth based on INTERGROWTH-21^st gender-specific standards. Fetus-specific estimated fetal weight (EFW) trajectories were calculated by linear mixed-effects models using data up to a fixed gestational age (GA) cutoff (28, 32, or 36 weeks) for fetuses having two or more measurements before the GA cutoff and not already delivered. A screen test positive for single biometry was based on Z-scores of EFW at the last scan before each GA cut-off so that the false positive rate (FPR) was 10%. Similarly, a screen test positive for the longitudinal analysis was based on the projected (extrapolated) EFW at 40 weeks from all available measurements before each cutoff for each fetus.

Results

Fetal abdominal and head circumference measurements, as well as birth weights in the Detroit population, matched well to the INTERGROWTH-21^st standards, yet this was not the case for biparietal diameter (BPD) and femur length (FL) (up to 9% and 10% discrepancy for mean and confidence intervals, respectively), mainly due to differences in the measurement technique. Single biometry based on EFW at the last scan at ≤32 weeks (GA IQR: 27.4–30.9 weeks) had a sensitivity of 50% and 53% (FPR = 10%) to detect preterm and term SGA and LGA neonates, respectively (AUC of 82% both). For the detection of LGA using data up to 32- and 36-week cutoffs, single biometry analysis had higher sensitivity than longitudinal analysis (52% vs 46% and 62% vs 52%, respectively; both p<0.05). Restricting the analysis to subjects with the last observation taken within two weeks from the cutoff, the sensitivity for detection of LGA, but not SGA, increased to 65% and 72% for single biometry at the 32- and 36-week cutoffs, respectively. SGA screening performance was higher for preterm (<37 weeks) than for term cases (73% vs 46% sensitivity; p<0.05) for single biometry at ≤32 weeks.

Conclusions

When growth abnormalities are defined based on birth weight, growth velocity (captured in the longitudinal analysis) does not provide additional information when compared to the last measurement for predicting SGA and LGA neonates, with both approaches detecting one-half of the neonates (FPR = 10%) from data collected at ≤32 weeks. Unlike for SGA, LGA detection can be improved if ultrasound scans are scheduled as close as possible to the gestational-age cutoff when a decision regarding the clinical management of the patient needs to be made. Screening performance for SGA is higher for neonates that will be delivered preterm.

Prediction of stillbirth from maternal factors, fetal biometry and uterine artery Doppler at 19-24 weeks

OBJECTIVES

To evaluate the performance of screening for all stillbirths and those due to impaired placentation and unexplained or other causes using a combination of maternal factors, fetal biometry and uterine artery pulsatility index (UtA-PI) at 19-24 weeks' gestation and to compare this performance with that of screening by UtA-PI alone.

METHODS

This was a prospective screening study of 70 003 singleton pregnancies including 69 735 live births and 268 (0.38%) antepartum stillbirths; 159 (59%) were secondary to impaired placentation and 109 (41%) were due to other or unexplained causes. Multivariable logistic regression analysis was used to develop a model for prediction of stillbirth based on a combination of maternal factors, fetal biometry and UtA-PI.

RESULTS

Combined screening predicted 55% of all stillbirths, including 75% of those due to impaired placentation and 23% of those that were unexplained or due to other causes, at a false-positive rate of 10%. Within the impaired placentation group, the detection rate of stillbirth < 32 weeks' gestation was higher than that of stillbirth ≥ 37 weeks (88% vs 46%; P < 0.001). The performance of screening by the combined test was superior to that of selecting the high-risk group on the basis of UtA-PI > 90^th percentile for gestational age, which predicted 48% of all stillbirths, 70% of those due to impaired placentation and 15% of those that were unexplained or due to other causes.

CONCLUSIONS

Second-trimester screening by a combination of UtA-PI with maternal factors and fetal biometry can predict a high proportion of stillbirths and, in particular, those that are due to impaired placentation. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

[Detection of small for gestational age fetuses during third trimester ultrasound. A monocentric observational study]

OBJECTIVES

Fetus small for gestational age (SGA) screening rate is evaluated around 21,7 % in France. Recommendations were developed to improve the efficiency of ultrasound conducted in the third trimester (T3), because neonatal consequences can be significant. This study aims to evaluate screening of SGA during T3 ultrasound and to describe causes for failure and differences with the recommendations of CNGOF.

METHODS

All children born between 2011 and 2012 with a birth weight below the 3rd percentile were included in this observational, retrospective, monocentric study. We noted that the diagnosis of SGA was placed on file. Then, as recommended by the CNGOF, we calculated estimated fetal weight (EFW) with Hadlock 3 and Hadlock 4, and the corresponding percentiles, using the biometrics from the ultrasound report. We thus could evaluate a new screening rate with SGA fetus identified through this technique.

RESULTS

A total of 142 patients were included. By calculating correctly all EFW and checking abdominal circumference percentiles, the screening rate of SGA fetuses with T3 ultrasound increased from 40 % to 50 % and the overall screening rate (clinical and ultrasound) from 54 % to 66 %.

CONCLUSION

By following the recommendations we found a real improvement in fetal SGA screening rates to T3 ultrasound with a potential benefit for their care.

Contingent versus routine third-trimester screening for late fetal growth restriction

OBJECTIVE

To evaluate the use of third-trimester ultrasound screening for late fetal growth restriction (FGR) on a contingent basis, according to risk accrued in the second trimester, in an unselected population.

METHODS

Maternal characteristics, fetal biometry and second-trimester uterine artery (UtA) Doppler were included in logistic regression analysis to estimate risk for late FGR (birth weight < 3(rd) percentile, or 3(rd) -10(th) percentile plus abnormal cerebroplacental ratio or UtA Doppler, with delivery ≥ 34 weeks). Based on the second-trimester risk, strategies for performing contingent third-trimester ultrasound examinations in 10%, 25% or 50% of the cohort were tested against a strategy of routine ultrasound scanning in the entire population at 32 + 0 to 33 + 6 weeks.

RESULTS

Models were constructed based on 1393 patients and validated in 1303 patients, including 73 (5.2%) and 82 late FGR (6.3%) cases, respectively. At the second-trimester scan, the a-posteriori second-trimester risk (a-posteriori first-trimester risk (baseline a-priori risk and mean arterial blood pressure) combined with second-trimester abdominal circumference and UtA Doppler) yielded an area under the receiver-operating characteristics curve (AUC) of 0.81 (95% CI, 0.74-0.87) (detection rate (DR), 43.1% for a 10% false-positive rate (FPR)). The combination of a-posteriori second-trimester risk plus third-trimester estimated fetal weight (full model) yielded an AUC of 0.92 (95% CI, 0.88-0.96) (DR, 74% for a 10% FPR). Subjecting 10%, 25% or 50% of the study population to third-trimester ultrasound, based on a-posteriori second-trimester risk, gave AUCs of 0.81 (95% CI, 0.75-0.88), 0.84 (95% CI, 0.78-0.91) and 0.89 (95% CI, 0.84-0.94), respectively. Only the 50% contingent model proved statistically equivalent to performing routine third-trimester ultrasound scans (AUC, 0.92 (95% CI, 0.88-0.96), P = 0.11).

CONCLUSION

A strategy of selecting 50% of the study population to undergo third-trimester ultrasound examination, based on accrued risk in the second trimester, proved equivalent to routine third-trimester ultrasound scanning in predicting late FGR.

Prediction of small-for-gestational-age neonates: screening by biophysical and biochemical markers at 19-24 weeks

OBJECTIVE

To investigate the value of combined screening by maternal characteristics and medical history, fetal biometry and biophysical and biochemical markers at 19-24 weeks' gestation, for prediction of delivery of small-for-gestational-age (SGA) neonates, in the absence of pre-eclampsia (PE), and examine the potential value of such assessment in deciding whether the third-trimester scan should be at 32 and/or 36 weeks' gestation.

METHODS

This was a screening study in 7816 singleton pregnancies, including 389 (5.0%) that delivered SGA neonates with birth weight < 5(th) percentile (SGA < 5(th) ), in the absence of PE. Multivariable logistic regression analysis was used to determine if screening by a combination of maternal factors, fetal biometry, uterine artery pulsatility index (UtA-PI) and maternal serum concentrations of placental growth factor (PlGF) and α-fetoprotein (AFP) had significant contribution in predicting SGA neonates. A model was developed for selecting the gestational age for third-trimester assessment, at 32 and/or 36 weeks, based on the results of screening at 19-24 weeks.

RESULTS

Significant independent contributions to the prediction of SGA < 5(th) were provided by maternal factors, fetal biometry, UtA-PI and serum PlGF and AFP. The detection rate (DR) of such combined screening at 19-24 weeks was 100%, 78% and 42% for SGA < 5(th) delivering < 32, at 32-36 and ≥ 37 weeks' gestation, respectively, at a false-positive rate (FPR) of 10%. In a hypothetical model, it was estimated that if the desired objective of prenatal screening is to predict about 80% of the cases of SGA < 5(th) , it would be necessary to select 11% of the population at the 19-24-week assessment to be reassessed at 32 weeks and 44% to be reassessed at 36 weeks; 57% would not require a third-trimester scan.

CONCLUSION

Prenatal prediction of a high proportion of SGA neonates necessitates the undertaking of screening in the third trimester of pregnancy, in addition to assessment in the second trimester, and the timing of such screening, at 32 and/or 36 weeks, should be contingent on the results of the assessment at 19-24 weeks.

Prediction of small-for-gestational-age neonates: screening by maternal serum biochemical markers at 19-24 weeks

OBJECTIVE

To investigate the value of maternal serum concentrations of placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), pregnancy-associated plasma protein-A (PAPP-A), free β-human chorionic gonadotropin (β-hCG) and α-fetoprotein (AFP) at 19-24 weeks' gestation, in combination with maternal factors and fetal biometry, in the prediction of delivery of small-for-gestational-age (SGA) neonates, in the absence of pre-eclampsia (PE) and examine the potential value of such assessment in deciding whether the third-trimester scan should be performed at 32 and/or 36 weeks' gestation.

METHODS

This was a screening study in 9715 singleton pregnancies, including 481 (5.0%) that delivered SGA neonates with birth weight < 5(th) percentile (SGA < 5(th) ), in the absence of PE. Multivariable logistic regression analysis was used to determine if screening by a combination of maternal factors, Z-scores of fetal head circumference, abdominal circumference and femur length, and log10 multiples of the median (MoM) values of PlGF, sFlt-1, PAPP-A, free β-hCG or AFP had a significant contribution to the prediction of SGA neonates. A model was developed in selecting the gestational age for third-trimester assessment, at 32 and/or 36 weeks, based on the results of screening at 19-24 weeks.

RESULTS

Compared to the normal group, the mean log10 MoM value of PlGF was lower, AFP was higher and sFlt-1, PAPP-A and free β-hCG were not significantly different in the SGA < 5(th) group that delivered < 37 weeks. The detection rate (DR) of combined screening by maternal factors, fetal biometry and serum PlGF and AFP at 19-24 weeks was 100%, 76% and 38% for SGA < 5(th) delivering < 32, 32-36 and ≥ 37 weeks' gestation, respectively, at a false-positive rate (FPR) of 10%. In a hypothetical model, it was estimated that, if the desired objective of prenatal screening is to predict about 80% of the cases of SGA < 5(th) , it would be necessary to select 11% of the population at the 19-24-week assessment to be reassessed at 32 weeks and 46% to be reassessed at 36 weeks; 54% would not require a third-trimester scan.

CONCLUSION

Prenatal prediction of a high proportion of SGA neonates necessitates the undertaking of screening in the third trimester of pregnancy, in addition to assessment in the second trimester, and the timing of such screening, at 32 and/or 36 weeks, should be contingent on the results of the assessment at 19-24 weeks.

Prediction of small-for-gestational-age neonates: screening by fetal biometry at 19-24 weeks

OBJECTIVE

To investigate the value of fetal biometry at 19-24 weeks' gestation in the prediction of delivery of small-for-gestational-age (SGA) neonates, in the absence of pre-eclampsia (PE), and examine the potential value of such assessment in deciding whether the third-trimester scan should be at 32 and/or 36 weeks' gestation.

METHODS

This was a screening study in 88,187 singleton pregnancies, including 5003 (5.7%) that delivered SGA neonates with birth weight < 5(th) percentile (SGA < 5(th)). Multivariable logistic regression analysis was used to determine if screening by a combination of maternal characteristics and medical history and Z-scores of fetal head circumference (HC), abdominal circumference (AC) and femur length (FL) had significant contribution in predicting SGA neonates. A model was developed for selecting the gestational age for third-trimester assessment, at 32 and/or 36 weeks, based on the results of screening at 19-24 weeks.

RESULTS

Combined screening by maternal factors and fetal biometry at 19-24 weeks, predicted 76%, 58% and 44% of SGA < 5(th) delivering < 32, 32-36 and ≥ 37 weeks' gestation, respectively, at a false-positive rate (FPR) of 10%. The detection rate (DR) of SGA < 5(th) delivering at 32-36 weeks improved from 58% to 82% with screening at 32 weeks rather than at 19-24 weeks. Similarly, the DR of SGA < 5(th) delivering ≥ 37 weeks improved from 44% with screening at 19-24 weeks to 61% and 76% with screening at 32 and 36 weeks, respectively. In a hypothetical model, it was estimated that if the desired objective of prenatal screening is to predict about 80% of the cases of SGA < 5(th), it would be necessary to select 28% of the population at the 19-24-week assessment to be reassessed at 32 weeks and 41% to be reassessed at 36 weeks; in 59% of pregnancies there would be no need for a third-trimester scan.

CONCLUSION

Prenatal prediction of a high proportion of SGA neonates necessitates the undertaking of screening in the third trimester of pregnancy, in addition to assessment in the second trimester, and the timing of such screening, either at 32 and/or 36 weeks, should be contingent on the results of the assessment at 19-24 weeks.

Prediction of small-for-gestational-age neonates: screening by placental growth factor and soluble fms-like tyrosine kinase-1 at 35-37 weeks

OBJECTIVE

To investigate the potential value of maternal serum placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) at 35-37 weeks' gestation in the prediction of delivery of small-for-gestational-age (SGA) neonates, in the absence of pre-eclampsia (PE).

METHODS

This was a screening study in singleton pregnancies at 35-37 weeks, including 158 that delivered SGA neonates with birth weight < 5(th) percentile and 3701 cases unaffected by SGA, PE or gestational hypertension. Multivariable logistic regression analysis was used to determine if measuring serum levels of PlGF and sFlt-1 improved the prediction of delivery of SGA neonates provided by screening with maternal characteristics and medical history (maternal factors), and estimated fetal weight (EFW) from fetal head circumference, abdominal circumference and femur length.

RESULTS

Compared to the normal group, the median PlGF multiples of the median (MoM) was significantly lower and the median sFlt-1 MoM was significantly higher in the SGA group. Combined screening by maternal factors and EFW at 35-37 weeks predicted, at 10% false-positive rate (FPR), 90%, 92% and 94% of SGA neonates with birth weight < 10(th), < 5(th) and < 3(rd) percentiles, respectively, delivering < 2 weeks following assessment; the respective values for SGA delivering ≥ 37 weeks were 66%, 73% and 80%. When PlGF and sFlt-1 were added to a model that combines maternal factors and EFW, sFlt-1 did not remain as a significant independent predictor of SGA < 5(th). Combined screening by maternal factors, EFW and serum PlGF, predicted, at a 10% FPR, 88%, 96% and 94% of SGA neonates with birth weight < 10(th), < 5(th) and < 3(rd) percentiles, respectively, delivering < 2 weeks following assessment and the respective values for SGA delivering ≥ 37 weeks were 64%, 75% and 80%.

CONCLUSION

sFlt-1 does not provide significant independent prediction of SGA, in the absence of PE, in addition to combined testing by maternal factors and fetal biometry at 35-37 weeks; whilst the addition of PlGF alone marginally improves the performance of screening.