Evidence-based national guidelines for the management of suspected fetal growth restriction: comparison, consensus, and controversy

Abstract

Small for gestational age is usually defined as an infant with a birthweight <10th centile for a population or customized standard. Fetal growth restriction refers to a fetus that has failed to reach its biological growth potential because of placental dysfunction. Small-for-gestational-age babies make up 28-45% of nonanomalous stillbirths, and have a higher chance of neurodevelopmental delay, childhood and adult obesity, and metabolic disease. The majority of small-for-gestational-age babies are not recognized before birth. Improved identification, accompanied by surveillance and timely delivery, is associated with reduction in small-for-gestational-age stillbirths. Internationally and regionally, detection of small for gestational age and management of fetal growth problems vary considerably. The aim of this review is to: summarize areas of consensus and controversy between recently published national guidelines on small for gestational age or fetal growth restriction; highlight any recent evidence that should be incorporated into existing guidelines; and identify future research priorities in this field. A search of MEDLINE, Google, and the International Guideline Library identified 6 national guidelines on management of pregnancies complicated by fetal growth restriction/small for gestational age published from 2010 onwards. There is general consensus between guidelines (at least 4 of 6 guidelines in agreement) in early pregnancy risk selection, and use of low-dose aspirin for women with major risk factors for placental insufficiency. All highlight the importance of smoking cessation to prevent small for gestational age. While there is consensus in recommending fundal height measurement in the third trimester, 3 specify the use of a customized growth chart, while 2 recommend McDonald rule. Routine third-trimester scanning is not recommended for small-for-gestational-age screening, while women with major risk factors should have serial scanning in the third trimester. Umbilical artery Doppler studies in suspected small-for-gestational-age pregnancies are universally advised, however there is inconsistency in the recommended frequency for growth scans after diagnosis of small for gestational age/fetal growth restriction (2-4 weekly). In late-onset fetal growth restriction (≥32 weeks) general consensus is to use cerebral Doppler studies to influence surveillance and/or delivery timing. Fetal surveillance methods (most recommend cardiotocography) and recommended timing of delivery vary. There is universal agreement on the use of corticosteroids before birth at <34 weeks, and general consensus on the use of magnesium sulfate for neuroprotection in early-onset fetal growth restriction (<32 weeks). Most guidelines advise using cardiotocography surveillance to plan delivery in fetal growth restriction <32 weeks. The recommended gestation at delivery for fetal growth restriction with absent and reversed end-diastolic velocity varies from 32 to ≥34 weeks and 30 to ≥34 weeks, respectively. Overall, where there is high-q...

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

“…Several studies have reported, first, how best to monitor and deliver SGA neonates, second, that about 85% of SGA neonates are born at ≥ 37 weeks' gestation and, third, that the best prediction of a SGA neonate is achieved by routine ultrasound examination at 36 weeks' gestation. The findings of this study have highlighted the necessity to improve the performance of the 36‐week assessment in the prediction of both delivery of a SGA neonate and adverse perinatal outcome, and have demonstrated that these goals cannot be achieved by addition of fetal growth velocity between 32 and 36 weeks' gestation to EFW at 36 weeks.…”

Genetic syndromes associated with isolated fetal growth restriction

“…Fetal Growth Restriction (FGR), also known as Intra‐uterine Growth Restriction (IUGR), is a condition that classically was defined as an inappropriate fetal weight gain for a specific gestational age, or synonymously, as the impossibility to reach the fetal biological growth potential. Practically, FGR is demonstrated by the statistical deviation of an estimated fetal weight (EFW) or an abdominal circumference (AC) from a population‐based reference, with a typical threshold at the 10th, fifth or third centile. However, according to a recent expert consensus, this condition should be redefined and be restricted to the smallest fetuses, those with an EFW or an AC below the third centile, or impaired growth velocity, or alternatively to fetuses with an EFW below the 10th centile and a concomitant abnormal fetal or uterine Doppler.…”

Using cerebroplacental ratio in non‐SGA fetuses to predict adverse perinatal outcome: caution is required

“…A recent Delphi survey of experts defined late FGR (≥ 32 weeks) in the presence of at least two of: (1) abdominal circumference (AC) or estimated fetal weight (EFW) < 10 th centile, (2) AC/EFW crossing centiles of more than two quartiles on non‐customized growth charts, and (3) CPR < 5 th or UA‐PI > 95 th centile. Indeed, some professional bodies now incorporate consideration of the CPR when making decisions regarding appropriate surveillance and/or timing of birth in late‐onset small‐for‐gestational age (SGA) or FGR cases, as it is believed to be a better test for predicting adverse perinatal outcome than its individual UA and MCA Doppler components.…”

“…The management of late SGA/FGR is already covered by comprehensive recent reviews and protocols from various professional bodies, which include clear recommendations of the appropriate frequency of monitoring and timing of birth (summarized by McCowan et al …”