Diagnosis and management of fetal growth restriction: the ISUOG guideline and comparison with the SMFM guideline

The role of umbilical vein blood flow assessment in the prediction of fetal growth velocity and adverse outcome: a prospective observational cohort study

BACKGROUND

Identifying fetal growth restriction and distinguishing it from a constitutionally small fetus can be challenging. The umbilical vein blood flow is a surrogate parameter of the amount of oxygen and nutrients delivered to the fetus, providing valuable insights about the function of the placenta. Nevertheless, currently, this parameter is not used in the diagnosis and management of fetal growth restriction.

OBJECTIVE

To evaluate the umbilical vein blood flow and fetal growth velocity in small for gestational age fetuses and in fetal growth restriction, and to evaluate their capacity to predict adverse perinatal outcome and iatrogenic preterm birth. Secondly, to assess the correlation between umbilical vein blood flow and fetal growth velocity.

STUDY DESIGN

This was a prospective multicentric observational cohort study of women with a diagnosis of small for gestational age or fetal growth restriction in which fetal biometry and Doppler assessment, including umbilical vein blood flow measurement, were performed. The fetal growth velocity was derived from the difference between the estimated fetal weight calculated in 2 consecutive sonographic evaluations. The pregnancies were followed until delivery. Between-group differences were evaluated, and Pearson or Spearman correlation coefficients were reported to assess the relationship between variables of interest. Optimal cutoffs on the resulting receiver operating characteristic curve were determined and used to predict the outcomes of interest. Simple and multiple logistic regression models were estimated using umbilical vein blood flow and fetal growth velocity to predict adverse perinatal outcomes and iatrogenic preterm birth.

RESULTS

The study population included 64 small for gestational age and 58 growth restricted fetuses. When compared to reference ranges, small for gestational age fetuses had significantly lower fetal growth velocity and umbilical vein blood flow (P<.001). When compared to small for gestational age, fetuses with growth restriction had lower umbilical vein blood flow (P<.001), umbilical vein blood flow corrected for estimated fetal weight and abdominal circumference (P<.01 and P<.001), and fetal growth velocity (P<.001). Fetal growth velocity was positively correlated with umbilical vein blood flow (r=0.46, P<.001). The multivariable logistic regression analyses showed that, after adjusting for diagnosis of fetal growth restriction, umbilical vein blood flow ≤0.65 multiple of the median (adjusted odds ratio [aOR] 3.5; 95% confidence interval [CI] 1.0-11.8) and fetal growth velocity ≤0.63 multiple of the median (adjusted odds ratio 3.0, 95% CI 1.2-7.9) were associated with adverse perinatal outcome. Furthermore, when accounting for fetal growth restriction diagnosis, umbilical vein blood flow ≤0.60 multiple of the median (adjusted odds ratio 5.2, 95% CI 1.7-15.9), and fetal growth velocity ≤0.63 multiple of the median (adjusted odds ratio 3.6, 95% CI 1.1-12.6) were significant predictors of iatrogenic preterm birth.

CONCLUSION

Umbilical vein blood flow could play a role to identify fetuses with fetal growth restriction and to predict fetal growth at the subsequent biometric evaluation. We found a significant correlation between umbilical vein blood flow and fetal growth. Umbilical vein blood flow and fetal growth velocity are independent predictors of iatrogenic preterm birth and adverse perinatal outcome in a population of small fetuses, regardless of the Delphi consensus criteria. These results support future study on the predictive value of this parameter in fetuses with a suspected fetal growth restriction.

Fetal Growth Restriction: A Pragmatic Approach

An accurate diagnosis of fetal growth restriction relies on a precise estimation of gestational age based on a carefully obtained history as well as early ultrasound, since a difference of just a few days can lead to a significant error. There is a continuum of risk for adverse outcome that depends on the certainty of dates and presence or absence of comorbidities, in addition to the estimated fetal weight percentile and the umbilical artery waveform. The results of several studies, most notably the TRUFFLE trial, demonstrate that optimal management of fetal growth restriction with an abnormal umbilical artery waveform requires daily electronic fetal heart rate monitoring, and this monitoring does not require computerized interpretation. The role of ductus venosus waveform, biophysical profile, and middle cerebral artery waveform is less clear, and the results of these three modalities should be interpreted with caution. KEY POINTS: · A correct diagnosis of fetal growth restriction requires a very precise estimate of gestational age.. · In the presence of abnormal umbilical artery Doppler, the cornerstone of surveillance is daily electronic fetal heart rate monitoring.. · Surveillance with biophysical profile, ductus venosus waveform, and middle cerebral artery waveform are less important than daily electronic fetal heart rate monitoring..

Artificial Ex Utero Systems to Treat Severe Periviable Fetal Growth Restriction-A Possible Future Indication?

Fetal growth restriction, or intrauterine growth restriction, is a common gestational condition characterized by reduced intrauterine growth. However, severe periviable fetal growth restriction is still associated with elevated perinatal mortality and morbidity. The current literature advises delivery once it is deemed that fetal compromise is evident. As uteroplacental insufficiency is the most common etiology of this condition, we hypothesize that the use of artificial ex utero systems to provide adequate nutrition and recreate the uterine environment may be a viable treatment option in this situation, even with the possibility of treating severe fetal growth restriction and prevent sequelae. There are promising experimental studies in sheep models investigating the artificial ex utero system for potential prenatal conditions, but future additional investigation is needed before translating to clinical trials in humans.

Intrauterine Growth Restriction: Need to Improve Diagnostic Accuracy and Evidence for a Key Role of Oxidative Stress in Neonatal and Long-Term Sequelae

Intrauterine growth restriction (IUGR) and being small for gestational age (SGA) are two distinct conditions with different implications for short- and long-term child development. SGA is present if the estimated fetal or birth weight is below the tenth percentile. IUGR can be identified by additional abnormalities (pathological Doppler sonography, oligohydramnion, lack of growth in the interval, estimated weight below the third percentile) and can also be present in fetuses and neonates with weights above the tenth percentile. There is a need to differentiate between IUGR and SGA whenever possible, as IUGR in particular is associated with greater perinatal morbidity, prematurity and mortality, as well as an increased risk for diseases in later life. Recognizing fetuses and newborns being "at risk" in order to monitor them accordingly and deliver them in good time, as well as to provide adequate follow up care to ameliorate adverse sequelae is still challenging. This review article discusses approaches to differentiate IUGR from SGA and further increase diagnostic accuracy. Since adverse prenatal influences increase but individually optimized further child development decreases the risk of later diseases, we also discuss the need for interdisciplinary follow-up strategies during childhood. Moreover, we present current concepts of pathophysiology, with a focus on oxidative stress and consecutive inflammatory and metabolic changes as key molecular mechanisms of adverse sequelae, and look at future scientific opportunities and challenges. Most importantly, awareness needs to be raised that pre- and postnatal care of IUGR neonates should be regarded as a continuum.

Early-onset fetal growth restriction: comparison of two management protocols in a single tertiary center

OBJECTIVE

Compare the neonatal outcomes of two protocols of diagnosis and surveillance of pregnancies complicated by early-onset FGR in a tertiary hospital.

METHODS

This is a retrospective cohort study of pregnant women diagnosed with early-onset FGR between 2017 and 2020. We compared the obstetric and perinatal outcomes between two different management protocols (before and after 2019).

RESULTS

Seventy-two cases of early-onset FGR were diagnosed in the forementioned period: 45 (62.5%) were managed according to protocol 1 and 27 (37.5%) according to protocol 2. Mean gestational age at delivery was significantly different between groups: 34.9 ± 3.1 weeks (95% CI 34.0-35.9) in group 1 and 32.3 ± 4.4 weeks (95% CI 30.4-33.9) in group 2. 74.1% (20) of newborns in group 2 were admitted in de NICU, a significant difference when compared with 46.7% of group 1. There were no statistically significant differences in the remaining serious neonatal adverse outcomes.

CONCLUSIONS

This is the first study published comparing two different protocols of management of FGR. The implementation of the new protocol seems to have led to a decrease in the number of fetuses labeled as growth restricted and to a decrease in the gestational age of delivery of such fetuses, but without increasing the rate of serious neonatal adverse outcomes.

SYNOPSIS

The implementation of the 2016 ISUOG guidelines for the diagnosis of fetal growth restriction seems to have led to a decrease in the number of fetuses labeled as growth restricted and to a decrease in the gestational age of delivery of such fetuses, but without increasing the rate of serious neonatal adverse outcomes.

Do differences in diagnostic criteria for late fetal growth restriction matter?

BACKGROUND

Criteria for diagnosis of fetal growth restriction differ widely according to national and international guidelines, and further heterogeneity arises from the use of different biometric and Doppler reference charts, making the diagnosis of fetal growth restriction highly variable.

OBJECTIVE

This study aimed to compare fetal growth restriction definitions between Delphi consensus and Society for Maternal-Fetal Medicine definitions, using different standards/charts for fetal biometry and different reference ranges for Doppler velocimetry parameters.

STUDY DESIGN

From the TRUFFLE 2 feasibility study (856 women with singleton pregnancy at 32+0 to 36+6 weeks of gestation and at risk of fetal growth restriction), we selected 564 women with available mid-pregnancy biometry. For the comparison, we used standards/charts for estimated fetal weight and abdominal circumference from Hadlock, INTERGROWTH-21st, and GROW and Chitty. Percentiles for umbilical artery pulsatility index and its ratios with middle cerebral artery pulsatility index were calculated using Arduini and Ebbing reference charts. Sensitivity and specificity for low birthweight and adverse perinatal outcome were evaluated.

RESULTS

Different combinations of definitions and reference charts identified substantially different proportions of fetuses within our population as having fetal growth restriction, varying from 38% (with Delphi consensus definition, INTERGROWTH-21st biometric standards, and Arduini Doppler reference ranges) to 93% (with Society for Maternal-Fetal Medicine definition and Hadlock biometric standards). None of the different combinations tested appeared effective, with relative risk for birthweight <10th percentile between 1.4 and 2.1. Birthweight <10th percentile was observed most frequently when selection was made with the GROW/Chitty charts, slightly less with the Hadlock standard, and least frequently with the INTERGROWTH-21st standard. Using the Ebbing Doppler reference ranges resulted in a far higher proportion identified as having fetal growth restriction compared with the Arduini Doppler reference ranges, whereas Delphi consensus definition with Ebbing Doppler reference ranges produced similar results to those of the Society for Maternal-Fetal Medicine definition. Application of Delphi consensus definition with Arduini Doppler reference ranges was significantly associated with adverse perinatal outcome, with any biometric standards/charts. The Society for Maternal-Fetal Medicine definition could not accurately detect adverse perinatal outcome irrespective of estimated fetal weight standard/chart used.

CONCLUSION

Different combinations of fetal growth restriction definitions, biometry standards/charts, and Doppler reference ranges identify different proportions of fetuses with fetal growth restriction. The difference in adverse perinatal outcome may be modest, but can have a significant impact in terms of rate of intervention.

Postnatal genetic and neurodevelopmental assessment in infants born at term with severely low birth weight of non-placental origin

OBJECTIVE

To determine the frequency of genetic syndromes and childhood neurodevelopmental impairment in non-malformed infants born at term with severely low birth weight and no evidence of placental insufficiency.

METHODS

This case series was constructed from the data of infants delivered at term between 2013 and 2018 with severely low birth weight, defined as birth weight more than 2.5 SD below the mean, with normal maternal and fetal Doppler (umbilical artery, fetal middle cerebral artery, cerebroplacental ratio and uterine artery) and no maternal hypertensive disorder during pregnancy or fetal structural anomaly on prenatal ultrasound examination. Clinical exome sequencing and copy number variation (CNV) analysis were performed using DNA extracted from the children's saliva. Cognitive and psychomotor development was evaluated using the Bayley Scales of Infant and Toddler Development, 3rd edition or the Wechsler Intelligence Scale for Children, 5th edition tests, according to the child's age at testing.

RESULTS

Among the 36 405 infants born within the study period, 274 (0.75%) had a birth weight below -2.5 SD, of whom 98 met the inclusion criteria. Among the 63 families contacted, seven (11%) reported a postnatal diagnosis of a genetic syndrome and a further 18 consented to participate in the study. Median gestational age at delivery was 38.0 (interquartile range (IQR), 37.3-38.5) weeks and median birth weight was 2020 (IQR, 1908-2248) g. All 18 children showed a normal result on clinical exome sequencing and CNV analysis, but six (33%) obtained a low score on neurodevelopmental testing.

CONCLUSION

Non-malformed severely small term infants with no clinical or Doppler signs of placental insufficiency present a high rate of genetic syndromes and neurodevelopmental impairment during childhood. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Fetal growth disorders in twin gestations

PURPOSE OF REVIEW

Twin gestations account for approximately 3% of all births. Although there appear to be physiologic differences in the third trimester growth of twins compared with singleton gestations, reasons for this remain unclear. As growth-restricted fetuses and neonates are at increased risk for adverse outcomes, there is a clinical need to optimize our ability to delineate normally from pathologically grown twins.

RECENT FINDINGS

Recent studies have addressed current limitations in the way growth restriction is diagnosed in twin gestations. Twin-specific fetal and neonatal growth charts have been shown to decrease the number of cases inappropriately labeled as growth restricted compared with singleton nomograms. In addition, individual growth assessment (IGA) is a promising method of diagnosing pathological growth using each fetus's growth potential rather than a comparison of the estimated fetal weight with population nomograms.

SUMMARY

There is a recent focus on improving our understanding of physiologic and pathologic twin growth. The increased use of twin-specific growth curves is likely to result in a decrease in the incidence of FGR diagnosis among twin gestations and could improve the outcomes of twins currently misclassified as FGR. Future research will hopefully clarify the reasons behind differences seen in twin versus singleton third trimester twin growth.

Definitions matter: detection rates and perinatal outcome for infants classified prenatally as having late fetal growth restriction using SMFM biometric vs ISUOG/Delphi consensus criteria

OBJECTIVES

Fetal growth restriction (FGR) is often secondary to placental dysfunction and is suspected prenatally based on biometric or circulatory abnormalities detected on ultrasound. The aims of this study were to compare the screening performance of the Society for Maternal-Fetal Medicine (SMFM) biometric criteria (estimated fetal weight (EFW) or abdominal circumference (AC) < 10th centile) with that of the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG)-endorsed Delphi consensus criteria for late FGR for delivery of a small-for-gestational-age (SGA) infant at term, emergency Cesarean section (CS) for non-reassuring fetal status (NRFS), perinatal mortality and composite severe neonatal morbidity.

METHODS

We classified retrospectively non-anomalous singleton infants as having late FGR (diagnosed ≥ 32 weeks) according to SMFM and ISUOG/Delphi criteria in a cohort of women who had been referred to the Mater Mother's Hospital, Brisbane, Australia and who delivered at term between January 2014 and December 2020. The study outcomes were delivery of a SGA infant (birth weight (BW) < 10th or < 3rd centile), emergency CS for NRFS, perinatal mortality (defined as stillbirth or neonatal death within 28 days of a live birth) and a composite of severe neonatal morbidity. We assessed the screening performance of various ultrasound variables by calculating the sensitivity, specificity, positive (PPV) and negative (NPV) predictive values, false-positive and false-negative rates, positive likelihood ratio (LR+) and negative likelihood ratio.

RESULTS

The SMFM and ISUOG/Delphi consensus criteria collectively classified 1030 cases as having late FGR. Of these, 400 cases were classified by both SMFM and ISUOG/Delphi criteria, whilst 548 cases were classified using only SMFM criteria and 82 cases were classified only by ISUOG/Delphi criteria. Prenatal detection of late FGR by SMFM and ISUOG/Delphi criteria was associated with increased odds of delivery of an infant with BW < 10th centile (SMFM: adjusted odds ratio (aOR), 133.0 (95% CI, 94.7-186.6); ISUOG/Delphi: aOR, 69.5 (95% CI, 49.1-98.2)) or BW < 3rd centile (SMFM: aOR, 348.7 (95% CI, 242.6-501.2); ISUOG/Delphi: aOR, 215.4 (95% CI, 148.4-312.7)). Compared with the SMFM criteria, the ISUOG/Delphi criteria were associated with lower odds (aOR, 0.5 (95% CI, 0.3-0.8)) of predicting a SGA infant with BW < 10th centile, but higher odds of predicting emergency CS for NRFS (aOR, 2.30 (95% CI, 1.14-4.66)) and composite neonatal morbidity (aOR, 1.22 (95% CI, 1.05-1.41)). Both SMFM and ISUOG/Delphi criteria were associated with high LR+, specificity, PPV and NPV for the prediction of infants with BW < 10th and BW < 3rd centile. However, both methods functioned much less efficiently for the prediction of composite severe neonatal morbidity or emergency CS for NRFS, with LR+ < 10. The SMFM biometric criteria alone, particularly AC < 3rd centile, had the highest LR+ values for the prediction of perinatal mortality.

CONCLUSION

Both the SMFM and ISUOG/Delphi criteria had strong screening potential for the detection of infants with BW < 10th or < 3rd centile but not for adverse neonatal outcome. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Differences in placental oxygenation and perfusion status between fetal growth-restricted and small-for-gestational-age pregnancies: a functional magnetic resonance imaging study

OBJECTIVE

Functional magnetic resonance imaging (MRI) can assess oxygenation and perfusion status in the placenta. We aimed to explore the differences in functional parameters between pregnancies complicated by fetal growth restriction (FGR) and small-for-gestational-age (SGA).

METHODS

This was a prospective study. A pregnancy complicated by SGA was defined by prenatal ultrasonic estimated fetal weight (EFW) and a final birthweight < the 10th percentile. A pregnancy complicated by FGR was defined as a more severe subtype (ultrasonic EFW < the 3rd percentile or abnormal Doppler results). All pregnant women underwent T2* and intravoxel incoherent motion (IVIM) scans using a 3.0-T MRI scanner. Functional parameters in the control, SGA, and FGR groups, namely, the T2* Z score, apparent diffusion coefficient (ADC), diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f), were calculated and compared.

RESULTS

In total, 30 pregnancies complicated by SGA, 24 pregnancies complicated by FGR, and 28 control pregnancies were included in the final analysis. Oxygenation status, as assessed by the T2* Z score, was significantly lower in pregnancies complicated by FGR than in pregnancies complicated by SGA (p < 0.001). However, diffusion and perfusion parameters, including the ADC, D, D*, and f, were similar between pregnancies complicated by SGA and FGR (p > 0.05 for all). Compared to the control pregnancies, all the parameters were significantly decreased in the SGA and FGR groups, except for the D* value. The T2* Z score, ADC, and D values were negatively correlated with birthweight.

CONCLUSION

Although both pregnancies complicated by SGA and FGR were associated with significantly lower oxygenation and perfusion than normal control pregnancies, placental hypoxia seemed to be more predominant in pregnancies complicated by FGR than in pregnancies complicated by SGA.

KEY POINTS

• Pregnancy complicated by FGR was associated with a more severe type of hypoxia than pregnancy complicated by SGA. • The diffusion and perfusion parameters of pregnancies complicated by SGA and FGR were similar. • SGA may represent another growth disorder that is not entirely healthy.

Reduced fetal growth velocity and weight loss are associated with adverse perinatal outcome in fetuses at risk of growth restriction

BACKGROUND

Although fetal size is associated with adverse perinatal outcome, the relationship between fetal growth velocity and adverse perinatal outcome is unclear.

OBJECTIVE

This study aimed to evaluate the relationship between fetal growth velocity and signs of cerebral blood flow redistribution, and their association with birthweight and adverse perinatal outcome.

STUDY DESIGN

This study was a secondary analysis of the TRUFFLE-2 multicenter observational prospective feasibility study of fetuses at risk of fetal growth restriction between 32⁺⁰ and 36⁺⁶ weeks of gestation (n=856), evaluated by ultrasound biometry and umbilical and middle cerebral artery Doppler. Individual fetal growth velocity was calculated from the difference of birthweight and estimated fetal weight at 3, 2, and 1 week before delivery, and by linear regression of all available estimated fetal weight measurements. Fetal estimated weight and birthweight were expressed as absolute value and as multiple of the median for statistical calculation. The coefficients of the individual linear regression of estimated fetal weight measurements (growth velocity; g/wk) were plotted against the last umbilical-cerebral ratio with subclassification for perinatal outcome. The association of these measurements with adverse perinatal outcome was assessed. The adverse perinatal outcome was a composite of abnormal condition at birth or major neonatal morbidity.

RESULTS

Adverse perinatal outcome was more frequent among fetuses whose antenatal growth was <100 g/wk, irrespective of signs of cerebral blood flow redistribution. Infants with birthweight <0.65 multiple of the median were enrolled earlier, had the lowest fetal growth velocity, higher umbilical-cerebral ratio, and were more likely to have adverse perinatal outcome. A decreasing fetal growth velocity was observed in 163 (19%) women in whom the estimated fetal weight multiple of the median regression coefficient was <-0.025, and who had higher umbilical-cerebral ratio values and more frequent adverse perinatal outcome; 67 (41%; 8% of total group) of these women had negative growth velocity. Estimated fetal weight and umbilical-cerebral ratio at admission and fetal growth velocity combined by logistic regression had a higher association with adverse perinatal outcome than any of those parameters separately (relative risk, 3.3; 95% confidence interval, 2.3-4.8).

CONCLUSION

In fetuses at risk of late preterm fetal growth restriction, reduced growth velocity is associated with an increased risk of adverse perinatal outcome, irrespective of signs of cerebral blood flow redistribution. Some fetuses showed negative growth velocity, suggesting catabolic metabolism.

Effects of psychiatric disorders on ultrasound measurements and adverse perinatal outcomes in Chinese pregnant women: A ten-year retrospective cohort study

BACKGROUND

Placental health and serial fetal ultrasound parameters deficits in fetal development in women with psychiatric disorders have yet to be understood. This study aimed to examine the effects of psychiatric disorders on placental health, ultrasound measurements, and adverse perinatal outcomes among Chinese pregnant women.

METHODS

All the pregnant women with psychiatric disorders who delivered at Women's Hospital School of Medicine, Zhejiang University, China, between 2010 and 2020 were included. A total of 992 women (716 in the healthy control group and 276 in the psychiatric disorders group) were recruited. Outcomes include maternal and neonatal birth outcomes. Linear and logistic regression models were used to determine the beta (β) and odds ratios (OR) across 2 models after adjusting for multiple covariates.

RESULTS

For women with psychiatric diagnoses, the mean placental measurements and serial fetal ultrasound parameters, and neonatal birth weight were lower than general pregnant women. After controlling the use of psychotropic medication during pregnancy, women with psychiatric diagnoses showed higher rates of placental implantation abnormalities or placental adhesion (OR = 5.724, 95% CI = [1.805, 15.408]), gestational diabetes mellitus (OR = 3.861, 95% CI = [2.109, 7.068]), anemia in pregnancy (OR = 4.944, 95% CI = [2.306, 10.598]), preterm birth <37 weeks' gestation (OR = 3.200, 95% CI = [1.702, 6.016]), low birth weight (OR = 11.299, 95% CI = [4.068, 31.386]), and neonatal intensive care unit admission (OR = 3.143, 95% CI = [1.656, 5.962]) compared to women in the healthy control group.

CONCLUSION

Pregnant women with psychiatric disorders were more likely to have poor placental outcomes, more ultrasound parameter abnormalities and obstetrical complications, and a higher risk for adverse birth outcomes.

Current practice in the diagnosis and management of fetal growth restriction: An international survey

INTRODUCTION

The aim of this survey was to evaluate the current practice in respect of diagnosis and management of fetal growth restriction among obstetricians in different countries.

MATERIAL AND METHODS

An e-questionnaire was sent via REDCap with "click thru" links in emails and newsletters to obstetric practitioners in different countries and settings with different levels of expertise. Clinical scenarios in early and late fetal growth restriction were given, followed by structured questions/response pairings.

RESULTS

A total of 275 participants replied to the survey with 87% of responses complete. Participants were obstetrician/gynecologists (54%; 148/275) and fetal medicine specialists (43%; 117/275), and the majority practiced in a tertiary teaching hospital (56%; 153/275). Delphi consensus criteria for fetal growth restriction diagnosis were used by 81% of participants (223/275) and 82% (225/274) included a drop in fetal growth velocity in their diagnostic criteria for late fetal growth restriction. For early fetal growth restriction, TRUFFLE criteria were used for fetal monitoring and delivery timing by 81% (223/275). For late fetal growth restriction, indices of cerebral blood flow redistribution were used by 99% (250/252), most commonly cerebroplacental ratio (54%, 134/250). Delivery timing was informed by cerebral blood flow redistribution in 72% (176/244), used from ≥32 weeks of gestation. Maternal biomarkers and hemodynamics, as additional tools in the context of early-onset fetal growth restriction (≤32 weeks of gestation), were used by 22% (51/232) and 46% (106/230), respectively.

CONCLUSIONS

The diagnosis and management of fetal growth restriction are fairly homogeneous among different countries and levels of practice, particularly for early fetal growth restriction. Indices of cerebral flow distribution are widely used in the diagnosis and management of late fetal growth restriction, whereas maternal biomarkers and hemodynamics are less frequently assessed but more so in early rather than late fetal growth restriction. Further standardization is needed for the definition of cerebral blood flow redistribution.

Severity of small-for-gestational-age and morbidity and mortality among very preterm neonates

OBJECTIVE

Evaluate the association between small for gestational age (SGA) severity and morbidity and mortality in a contemporary, population of very preterm infants.

STUDY DESIGN

This secondary analysis of a California statewide database evaluated singleton infants born during 2008-2018 at 24-32 weeks' gestation, with a birthweight <15th percentile. We analyzed neonatal outcomes in relation to weight for gestational age (WGA) and symmetry of growth restriction.

RESULTS

An increase in WGA by one z-score was associated with decreased major morbidity or mortality risk (aRR 0.73, 95% CI 0.68-0.77) and other adverse outcomes. The association was maintained across gestational ages and did not differ by fetal growth restriction diagnosis. Symmetric growth restriction was not associated with neonatal outcomes after standardizing for gestational age at birth.

CONCLUSIONS

Increasing SGA severity had a significant impact on neonatal outcomes among very preterm infants.

The role of the fetal biophysical profile in the management of fetal growth restriction

Growth-restricted fetuses are at risk of hypoxemia, acidemia, and stillbirth because of progressive placental dysfunction. Current fetal well-being, neonatal risks following delivery, and the anticipated rate of fetal deterioration are the major management considerations in fetal growth restriction. Surveillance has to quantify the fetal risks accurately to determine the delivery threshold and identify the testing frequency most likely to capture future deterioration and prevent stillbirth. From the second trimester onward, the biophysical profile score correlates over 90% with the current fetal pH, and a normal score predicts a pH >7.25 with a 100% positive predictive value; an abnormal score on the other hand predicts current fetal acidemia with similar certainty. Between 30% and 70% of growth-restricted fetuses with a nonreactive heart rate require biophysical profile scoring to verify fetal well-being, and an abnormal score in 8% to 27% identifies the need for delivery, which is not suspected by Doppler findings. Future fetal well-being is not predicted by the biophysical profile score, which emphasizes the importance of umbilical artery Doppler and amniotic fluid volume to determine surveillance frequency. Studies with integrated surveillance strategies that combine frequent heart rate monitoring with biophysical profile scoring and Doppler report better outcomes and stillbirth rates of between 0% and 4%, compared with those between 8% and 11% with empirically determined surveillance frequency. The variations in clinical behavior and management challenges across gestational age are better addressed when biophysical profile scoring is integrated into the surveillance of fetal growth restriction. This review aims to provide guidance on biophysical profile scoring in the in- and outpatient management of fetal growth restriction.