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

Routine third-trimester ultrasound assessment for intrauterine growth restriction

Intrauterine growth restriction significantly impacts perinatal outcomes. Undetected IUGR escalates the risk of adverse outcomes. Serial symphysis-fundal height measurement, a recommended strategy, is insufficient in detecting abnormal fetal growth. Routine third-trimester ultrasounds significantly improve detection rates compared with this approach, but direct high-quality evidence supporting enhanced perinatal outcomes from routine scanning is lacking. In assessing fetal growth, abdominal circumference alone performs comparably to estimated fetal weight. Hadlock formulas demonstrate accurate fetal weight estimation across diverse gestational ages and settings. When choosing growth charts, prescriptive standards (encompassing healthy pregnancies) should be prioritized over descriptive ones. Customized fetal standards may enhance antenatal IUGR detection, but conclusive high-quality evidence is elusive. Emerging observational data suggest that longitudinal fetal growth assessment could predict adverse outcomes better. However, direct randomized trial evidence supporting this remains insufficient.

Insufficient antenatal identification of fetal growth restriction leading to intrauterine fetal death: a regional population-based study in Japan

OBJECTIVE

Fetal growth restriction (FGR) is associated with perinatal adverse outcomes including intrauterine fetal death. Antenatally unidentified FGR has a higher risk of intrauterine fetal death than that identified antenatally. We, therefore, investigated the antenatal identification of FGR among intrauterine fetal deaths, and assessed the perinatal factors associated with the identification of FGR.

METHODS

This retrospective and population-based study reviewed all stillbirths in Shiga Prefecture, Japan, from 2007 to 2016 with exclusion criteria of multiple births, births at unidentified gestational weeks or < 22 gestational weeks, and lethal disorders. We analyzed cases of FGR, using the Japanese clinical definition: Z-score of estimated fetal weight for gestational age <-1.5 standard deviations (SD).

RESULTS

We identified 94 stillbirths with FGR among 429 stillbirths. Thirty-seven cases were antenatally identified during pregnancy management (39%). Dividing cases by a Z-score of -2.5 SD, 51 cases were classified as ≤-2.5 SD. Twenty-eight of the 51 cases (55%) with a Z-score <-2.5 SD were antenatally identified as having FGR, whereas 9 of the 43 cases (21%) with a Z-score ≥-2.5 SD were antenatally identified as having FGR (p = .002). Among cases with a Z-Score <-2.5 SD, 16 of 21 (76%) beyond 28 weeks' gestation and 12 of 30 (40%) before 28weeks' gestation were antenatally identified as having FGR (p = .023).

CONCLUSION

Fetal growth restriction leading to intrauterine fetal death in Japan was antenatally identified in less than half of cases. Antenatal identification of FGR was associated with the severity of growth restriction.

Predictors of adverse perinatal outcome up to 34 weeks, a multivariable analysis study

The objective was to evaluate the best predictors of adverse perinatal outcome (APO) in foetuses examined up to 34 weeks and delivered by spontaneous or induced labour. This was a retrospective study of 129 pregnancies that underwent an ultrasound Doppler examination at 23-34 weeks and entered into labour within 30 days. Cerebroplacental ratio (CPR) and mean uterine artery pulsatility index (mUtA PI) were converted into multiples of the median (MoM) and estimated foetal weight (EFW) into centiles to adjust for gestational age (GA). Sonographic and clinical parameters were evaluated using logistic regression analysis.The multivariable model for the prediction of APO presented a notable accuracy: Detection rate (DR) was 39.5% for a false positive rate (FPR) of 5% and 56.8% for a FPR of 10%, AUC 0.82, p < .0001. Significant predictors were GA, EFW centile, and CPR MoM, but not mUtA PI MoM. Moreover, the type of labour onset did not exert any influence on APO. In conclusion, up to 34 weeks, prediction of APO after spontaneous or induced labour may be done measuring CPR and EFW.IMPACT STATEMENTWhat is already known on this subject? Earlier in pregnancy, foetal growth restriction is caused by placental disease causing progressive hemodynamic changes. These changes have been exhaustively described. Conversely, information about the best predictors of adverse outcome is scarce.What do the results of this study add? The findings of this study show that prior to 34 weeks and up to 1 month before labour, labour outcome might be predicted by gestational age, foetal cerebroplacental ratio (CPR) and estimated foetal weight (EFW).What are the implications of these findings for clinical practice and/or further research? If CPR behaves as a good marker of outcome not only at the end of pregnancy but also earlier in gestation, it might be interrogated along with EFW in foetuses attempting vaginal delivery to determine the risk of adverse outcome.

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.

Antenatal screening of small for gestational age: Impact on obstetrical management and neonatal outcomes in case of trial of labor after 37 weeks

OBJECTIVE

Antenatal screening of small fetuses for gestational age (SGA) is a public health challenge. The aim of this study is to assess the obstetrical management and the immediate neonatal outcomes, according to the antenatal screening of the SGA fetuses.

METHODS

We performed a retrospective study in a French tertiary care hospital between January 1, 2016 and December 31, 2018. Women were eligible if they had a monofetal pregnancy with a fetus in head presentation and a trial of labor after 37 weeks. A fetus was considered SGA when the estimated fetal weight was less than the 10^th percentile at the third trimester ultrasound. A newborn was considered hypotrophic when the birthweight was less than the 10th percentile.

RESULTS

8 153 newborns were included and 948 of the newborns were hypotrophic (308 were suspected for SGA, 640 were not suspected for SGA) and 7205 were eutrophic. Among the hypotrophic neonates, we observed no significant difference regarding the immediate neonatal outcomes between the two groups of fetuses suspected and not suspected for SGA. Among the fetuses not suspected for SGA, the rate of arterial umbilical cord pH below 7.10 was significantly higher in the hypotrophic newborns compared to the non hypotrophic newborns (4.7% vs 3.1%, p = 0.041).

CONCLUSION

In our population, unsuspected fetal hypotrophy may be associated with an increased risk of neonatal acidosis. These results emphasize the benefit of improving prenatal screening to identify the SGA fetuses.

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.

Comparison of estimated fetal weight percentiles near term for predicting extremes of birthweight percentile

BACKGROUND

The INTERGROWTH-21st estimated fetal weight percentiles are recommended for predicting extremes of birthweight percentile, although evidence for their superiority over the widely employed Hadlock method is lacking.

OBJECTIVE

This study aimed to compare the ability of estimated fetal weight percentiles calculated using the Hadlock method and the INTERGROWTH-21st method to predict extremes of birthweight percentile.

STUDY DESIGN

A prospective cohort study of blinded serial ultrasonography in nulliparous women with a singleton pregnancy, The Pregnancy Outcome Prediction study was conducted in Cambridge, United Kingdom. The study participants who had a research estimated fetal weight performed at 36 weeks' gestation were eligible for the analysis. Estimated fetal weight percentiles for gestational age calculated using (1) the Hadlock method or (2) the INTERGROWTH-21st method were used as exposures. Birthweight percentiles of <10th (small for gestational age) and >90th (large for gestational age) for gestational age and fetal sex using the United Kingdom 1990 reference or the INTERGROWTH-21st birthweight reference were analyzed as outcomes using receiver operating characteristic curve analysis. Screening statistics from 2×2 tables were calculated for dichotomized exposures and each outcome.

RESULTS

The Hadlock estimated fetal weight percentile performed better than the INTERGROWTH-21st estimated fetal weight percentile at discriminating both small for gestational age birthweight (areas under the receiver operating characteristic curves, 0.87 vs 0.85; 95% confidence intervals, 0.85-0.89 vs 0.83-0.87, respectively; P<.0001) and large for gestational age birthweight (areas under the receiver operating characteristic curves, 0.87 vs 0.86; 95% confidence intervals, 0.85-0.90 vs 0.83-0.89, respectively; P=.005). When the estimated fetal weight percentiles were dichotomized and screen positive was defined at 90% specificity, the sensitivity for the Hadlock vs the INTERGROWTH-21st method was 58.6% vs 52.3%, respectively, for small for gestational age, and 71.0% vs 60.9%, respectively, for birthweight at less than the third percentile (United Kingdom 1990 reference). The results were similar when the birthweight percentile was defined using the INTERGROWTH-21st birthweight reference, when the estimated fetal weight was calculated without the inclusion of head measurements, or when the women who had clinically indicated scans and women who had their research scan result were excluded.

CONCLUSION

Replacing the Hadlock method by the INTERGROWTH-21st method may lead to less effective screening for extremes of birthweight percentile.

Sonographic growth curves versus neonatal birthweight growth curves for the identification of fetal growth restriction

OBJECTIVE

Fetal growth restriction is suspected when the estimated fetal weight is <10th percentile for gestational age. Using a regional sonographic estimated fetal weight growth curve to diagnose fetal growth restriction has no known benefits; however, the traditional approach of using birthweight curves is misleading, since a large proportion of preterm births arise from pathological pregnancies. Our aim was to compare the diagnostic accuracies of sonographic versus birthweight curves in diagnosing fetal growth restriction. Our secondary aim was to compare maternal, fetal and neonatal outcome based on these two approaches.

METHODS

Retrospective study based on computerized medical records. Included were women with a singleton pregnancy, that underwent fetal biometry between 24 and 36.6 weeks' gestation (January 2010-February 2016) and delivered in our center. Each pregnancy was assigned to one of three groups based on the earliest sonographic estimated fetal weight performed: G1-Appropriate for gestational age, G2-fetal growth restriction based on sonographic but not birthweight curves; or G3-fetal growth restriction based on birthweight growth curves. Demographics, obstetric characteristics, ultrasound data, and neonatal data were retrieved and compared between groups. Primary outcome: rate of small for gestational age neonates in each group. Secondary outcomes were various adverse maternal and neonatal outcomes.

RESULTS

Six thousand and five pregnancies met inclusion criteria. Of these 5386 (89.6%) were categorized as G1, 300 (5%) as G2 and 319 (5.3%) as G3. The rate of small for gestational age neonates differed significantly between groups: G1 9.2%, G2 39.7% and G3 70%. Multivariable logistic regression modeling reiterated these rates: the odds ratios for small for gestational age were 6.47 [95% CI 4.99-8.40] and 23.99 [95% CI 18.26-31.51] for G2 and G3 respectively. Prediction of small for gestational age based on sonographic EFW curves increased the sensitivity for detection of SGA from 26% to 41% with a slight decrease in specificity from 98% to 95%, and a decrease of the positive likelihood ratio from 18.4 to 7.7, however there was no significant change in the overall test accurcy; 88.5% to 87.1%. Secondary outcomes also differed between groups: G2 and G3 had similar rates of maternal and neonatal morbidities and most parameters were higher than G1. G2 and G3 showed lower mean gestational age at delivery (36.2 weeks and 35.9 weeks vs.37.8; p < .0001), and higher rates of preterm delivery (40% and 51.7% vs. 21.5%; p < .001), as well as higher rates of intrauterine fetal demise 3% in G2, 6.9% in G3 and 0.9% in G1, p < .0001.

CONCLUSION

Pregnancies that are currently managed as appropriate for gestational age based on birthweight curves, but classified as growth restricted when prenatal sonographic curves are used, are associated with higher rates of small for gestational age and poor perinatal outcomes, at rates comparable to pregnancies that are classified as growth restricted based on birthweight curves. Furthermore, applying sonographic curves increases the sensitivity for detection of small for gestational age neonates. Consequently, consideration should be given to the use of sonographic biometry curves for defining fetal growth restriction.

Could masking gestational age estimation during scanning improve detection of small-for-gestational-age fetuses? A controlled pre-post evaluation

BACKGROUND

Antenatal detection of small-for-gestational-age fetuses improves outcomes and reduces perinatal mortality rates. However, ultrasonographic estimation of fetal weight is subject to several potential sources of error. One potential source of error is subconscious operator bias towards "normal" measurement values for gestational age (observer-expectancy bias).

OBJECTIVE

We aimed to determine whether the sensitivity of small-for-gestational-age detection is improved by removing real-time display of estimated gestational age during measurement of the abdominal circumference in the third trimester.

STUDY DESIGN

This retrospective evaluation (November 2014-May 2018 inclusive) included all singleton infants liveborn at ≥28 weeks gestation in a single United Kingdom obstetrics center. In the preintervention phase, real-time estimated gestational age was displayed to sonographers as they measured fetal abdominal circumference (the key determinant of estimated fetal weight with the use of the INTERGROWTH 21st fetal weight equation) in the third trimester. In the postintervention phase, real-time gestational age information was removed on selected ultrasound machines. Accuracy of birthweight percentile estimation was assessed before and after intervention, both in the full cohort comprising all eligible scans and in a subcohort that was scanned within 4 weeks of delivery. We assessed the accuracy of small-for-gestational-age detection using the sensitivity, positive likelihood ratio, and area under the receiver-operator curve.

RESULTS

Of the 18,342 eligible pregnancies, 9342 (51%) had a third-trimester growth scan. The sensitivity of ultrasonographic estimation of fetal weight for antenatal detection of small-for-gestational-age babies did not change significantly between the before and after intervention phases (31.5% confidence interval, 27.1-36.2 vs 31.7% confidence interval, 20.2-45.0). Although the sensitivity for small-for-gestational-age detection was higher in the subcohort that was scanned within 4 weeks of delivery than in the full cohort (P<.001), there was no significant difference between the before and after intervention phases (58% confidence interval, 50-66 vs 65% confidence interval, 43-84). With the use of an estimation of the abdominal circumference percentile rather than estimated fetal weight percentile significantly decreased the sensitivity for small-for-gestational-age detection in all groups (P<.01), but there was no difference between the before and after intervention phases.

CONCLUSION

Blinding operators to the estimated gestation of the fetus during abdominal circumference measurement does not significantly alter the antenatal detection rate of small-for-gestational-age babies. The observer-expectancy effect is therefore unlikely to be a significant contributor to the error that is associated with ultrasonographic estimation of fetal weight.

Clinical significance of cerebroplacental ratio

PURPOSE OF REVIEW

Two-thirds of the pregnancies complicated by stillbirth demonstrate growth restriction. Identification of the foetus at risk of growth restriction is essential to reduce the risk of stillbirth. The aim of this review is to critically appraise the current evidence regarding clinical utility of cerebroplacental ratio (CPR) in antenatal surveillance.

RECENT FINDINGS

The CPR has emerged as an assessment tool for foetuses at increased risk of growth disorders. CPR is a better predictor of adverse events compared with middle-cerebral artery or umbilical artery Doppler alone. The predictive value of CPR for adverse perinatal outcomes is better for suspected small-for-gestational age foetuses compared with appropriate-for-gestational age (AGA) foetuses. CPR could be useful for the risk stratification of small-for-gestational age foetuses to determine the timing of delivery and also to calculate the risk of intrapartum compromise or prolonged admission to the neonatal care unit. Although there are many proposed cut-offs for an abnormal CPR value, evidence is currently lacking to suggest the use of one cut-off over another. CPR appears to be associated with increased risk of intrapartum foetal compromise, abnormal growth velocity, and lower birthweight in AGA foetuses as well. Moreover, birthweight differences are better explained with CPR compared to other factors such as ethnicity. However, the role of CPR in predicting adverse perinatal outcomes such as acidosis or low Apgar scores in AGA foetuses is yet to be determined.

SUMMARY

CPR appears to be a useful surrogate of suboptimal foetal growth and intrauterine hypoxia and it is associated with a variety of perinatal adverse events.

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 by fetal growth rate according to gestational age

BACKGROUND

Small-for-gestational age (SGA) infants should be identified before birth because of an increased risk of adverse perinatal outcomes. The objective of this study was to assess the impact of fetal growth rate by gestational age on the prediction of SGA and to identify the optimal time to initiate intensive fetal monitoring to detect SGA in low-risk women. We also sought to determine which the ultrasonographic parameters that contribute substantially to the birthweight determination.

METHODS

This was a retrospective study of 442 healthy pregnant women with singleton pregnancies. There were 328 adequate-for-gestational age (AGA) neonates and 114 SGA infants delivered between 37+0 and 41+6 weeks of gestation. We compared the biparietal diameters (BPD), head circumferences (HC), abdominal circumferences (AC), femur lengths (FL), and estimated fetal weights (EFW) obtained on each ultrasound to determine which of these parameters was the best indicator of SGA. We created receiver operating characteristic curves, calculated the areas under the curves (AUCs), and analyzed the data using multivariable logistic regressions to assess the ultrasound screening performances and identify the best predictive factor.

RESULTS

Among the four ultrasonographic parameters, the AC measurement between 24+0~28+6 weeks achieved a sensitivity of 79.5% and a specificity of 71.7%, with an AUC of 0.806 in the prediction of SGA. AC showed consistently higher AUCs above 0.8 with 64~80% sensitivities as gestational age progressed. EFW measurements from 33+0~35+6 gestational weeks achieved a sensitivity of 60.6% and a specificity of 87.6%, with an AUC of 0.826. In a conditional growth model developed from the linear mixed regression, the value differences between AC and EFW in the SGA and AGA groups became even more pronounced after 33+0~35+6 weeks.

CONCLUSION

Healthy low-risk women with a low fetal AC after 24 weeks' gestation need to be monitored carefully for fetal growth to identify SGA infants with a risk for adverse perinatal outcomes.

Fetal weight estimation at term - ultrasound versus clinical examination with Leopold's manoeuvres: a prospective blinded observational study

BACKGROUND

Fetal weight estimation is of key importance in the decision-making process for obstetric planning and management. The literature is inconsistent on the accuracy of measurements with either ultrasound or clinical examination, known as Leopold's manoeuvres, shortly before term. Maternal BMI is a confounding factor because it is associated with both the fetal weight and the accuracy of fetal weight estimation. The aim of our study was to compare the accuracy of fetal weight estimation performed with ultrasound and with clinical examination with respect to BMI.

METHODS

In this prospective blinded observational study we investigated the accuracy of clinical examination as compared to ultrasound measurement in fetal weight estimation, taking the actual birth weight as the gold standard. In a cohort of all consecutive patients who presented in our department from January 2016 to May 2017 to register for delivery at ≥37 weeks, examination was done by ultrasound and Leopold's manoeuvres to estimate fetal weight. All examiners (midwives and physicians) had about the same level of professional experience. The primary aim was to compare overall absolute error, overall absolute percent error, absolute percent error > 10% and absolute percent error > 20% for weight estimation by ultrasound and by means of Leopold's manoeuvres versus the actual birth weight as the given gold standard, namely separately for normal weight and for overweight pregnant women.

RESULTS

Five hundred forty-three patients were included in the data analysis. The accuracy of fetal weight estimation was significantly better with ultrasound than with Leopold's manoeuvres in all absolute error calculations made in overweight pregnant women. For all error calculations performed in normal weight pregnant women, no statistically significant difference was seen in the accuracy of fetal weight estimation between ultrasound and Leopold's manoeuvres.

CONCLUSIONS

Data from our prospective blinded observational study show a significantly better accuracy of ultrasound for fetal weight estimation in overweight pregnant women only as compared to Leopold's manoeuvres with a significant difference in absolute error. We did not observe significantly better accuracy of ultrasound as compared to Leopold's manoeuvres in normal weight women. Further research is needed to analyse the situation in normal weight women.

Fetal abdominal circumference in the second trimester and prediction of small for gestational age at birth

Background: Infants that are small for gestational age (SGA) at birth are at increased risk for morbidity and mortality. Unfortunately, the antenatal prediction of SGA is suboptimal.Objectives: We sought to: (1) examine the association between second trimester fetal abdominal circumference < 10% (2T-AClag) with SGA and other gestational and neonatal adverse outcomes; (2) assess 2T-AClag as a predictor of SGA.Study design: Retrospective study of 212 singleton gestations with 2T-AClag on routine ultrasound between 18-24 weeks. The study group was compared to 424 gestations without 2T-AClag for maternal characteristics as well as pregnancy and neonatal adverse outcomes. A multivariate logistic regression was used to determine the predictive value of 2T-AClag for SGA, adjusting for maternal and pregnancy characteristics. The screening model accuracy was assessed through receiver operating characteristic (ROC) curves. Fetal growth restriction (FGR) was defined as an estimated fetal weight (EFW) less than the 10th percentile.Results: Gestations with 2T-AClag had higher rates of SGA (35.7 versus 11.6%, p  <  .0001), FGR (17 versus 1.7%, p < .0001), pregnancy induced hypertension (31.1 versus 17%, p < .0001), preeclampsia (14.6 versus 7.8%, 0  =  0.01), abnormal umbilical artery Doppler (30 versus 5.1%, p < .0001), indicated preterm birth (5.7 versus 1.9%, p = .01), primary cesarean birth (29.6 versus 20.1%, p = .01) and NICU admission (12.9 versus 6.4%, p = .009). After adjusting for maternal and gestational risk factors, 2T-AClag remained an independent risk factor for SGA (OR 4.53, 95%CI 2.91-7.05, p < .0001) and FGR (OR 11.57, 95%CI 5.02-26.65, p < .0001). The inclusion of 2T-AClag in a regression model with traditional risk factors, significantly improved the model's predictability for SGA and FGR (area under ROC curve increased from 0.618 to 0.723 and 0.653 to 0.819, respectively, p < .0001).Conclusions: Second trimester abdominal circumference (AC) lag is associated with an increased risk of SGA, FGR and other adverse outcomes. The inclusion of 2T-AClag in a screening model for prediction of SGA and FGR may improve the identification of this at-risk group and assist in customizing surveillance plans.Brief rationaleScreening for newborns that are small for gestational age (SGA) at birth is currently suboptimal. Our study shows that second trimester abdominal circumference (AC) lag, using a parameter already routinely assessed during anatomic survey, is associated with SGA at birth and can improve current screening for growth restriction and other gestational, fetal and neonatal complications.

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.

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 Small for Gestational Age Infants in Healthy Nulliparous Women Using Clinical and Ultrasound Risk Factors Combined with Early Pregnancy Biomarkers

Objective

Most small for gestational age pregnancies are unrecognised before birth, resulting in substantial avoidable perinatal mortality and morbidity. Our objective was to develop multivariable prediction models for small for gestational age combining clinical risk factors and biomarkers at 15±1 weeks’ with ultrasound parameters at 20±1 weeks’ gestation.

Methods

Data from 5606 participants in the Screening for Pregnancy Endpoints (SCOPE) cohort study were divided into Training (n = 3735) and Validation datasets (n = 1871). The primary outcomes were All-SGA (small for gestational age with birthweight <10th customised centile), Normotensive-SGA (small for gestational age with a normotensive mother) and Hypertensive-SGA (small for gestational age with an hypertensive mother). The comparison group comprised women without the respective small for gestational age phenotype. Multivariable analysis was performed using stepwise logistic regression beginning with clinical variables, and subsequent additions of biomarker and then ultrasound (biometry and Doppler) variables. Model performance was assessed in Training and Validation datasets by calculating area under the curve.

Results

633 (11.2%) infants were All-SGA, 465(8.2%) Normotensive-SGA and 168 (3%) Hypertensive-SGA. Area under the curve (95% Confidence Intervals) for All-SGA using 15±1 weeks’ clinical variables, 15±1 weeks’ clinical+ biomarker variables and clinical + biomarkers + biometry /Doppler at 20±1 weeks’ were: 0.63 (0.59–0.67), 0.64 (0.60–0.68) and 0.69 (0.66–0.73) respectively in the Validation dataset; Normotensive-SGA results were similar: 0.61 (0.57–0.66), 0.61 (0.56–0.66) and 0.68 (0.64–0.73) with small increases in performance in the Training datasets. Area under the curve (95% Confidence Intervals) for Hypertensive-SGA were: 0.76 (0.70–0.82), 0.80 (0.75–0.86) and 0.84 (0.78–0.89) with minimal change in the Training datasets.

Conclusion

Models for prediction of small for gestational age, which combine biomarkers, clinical and ultrasound data from a cohort of low-risk nulliparous women achieved modest performance. Incorporation of biomarkers into the models resulted in no improvement in performance of prediction of All-SGA and Normotensive-SGA but a small improvement in prediction of Hypertensive-SGA. Our models currently have insufficient reliability for application in clinical practice however, they have potential utility in two-staged screening tests which include third trimester biomarkers and or fetal biometry.