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

ABSTRACT Objective To investigate the value of fetal biometry 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' gestation, comprising 278 that delivered SGA neonates with a birth weight < 5 th percentile and 5237 cases unaffected by SGA , PE or gestational hypertension. Multivariable logistic regression analysis was used to determine if screening by a combination of maternal factors and Z ‐scores of fetal head circumference ( HC ), abdominal circumference ( AC ) and femur length ( FL ) or estimated fetal weight ( EFW ) had a significant contribution to the prediction of SGA neonates. Results Multivariable logistic regression analysis demonstrated that the likelihood of delivering a SGA neonate with a birth weight < 5 th percentile decreased with maternal weight and height, and in parous women the risk increased with a longer interpregnancy interval. The risk was higher in women of Afro‐Caribbean and South Asian racial origins, in cigarette smokers, nulliparous women and in those with history of SGA , with or without prior PE . Combined screening by maternal characteristics and history with EFW Z ‐scores at 35–37 weeks predicted 89% of SGA neonates with birth weight < 5 th percentile delivering < 2 weeks following assessment, at a 10% false‐positive rate ( FPR ). The respective detection rate for the prediction of SGA neonates delivering ≥ 37 weeks' gestation was 70%. The performance of screening by a combination of Z‐scores of fetal HC , AC and FL was similar to that achieved by the EFW Z ‐score. Conclusion Combined testing by maternal characteristics and fetal biometry at 35–37 weeks could identify, at a 10% FPR , about 90% of pregnancies that subsequently deliver SGA neonates within 2 weeks of assessment and 70% of those that deliver ≥ 37 weeks. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.