Effect of regular third-trimester ultrasound examination on antenatal detection and perinatal outcomes of small for gestational age infants

Objective To assess the effect of regular third-trimester ultrasound on antenatal detection and perinatal outcomes of small for gestational age (SGA) infants. Methods Data from SGA infants delivered at >= 28 weeks' gestation were retrospectively studied. Each pregnancy had undergone three regular third-trimester ultrasound examinations, and data were grouped according to with or without antenatal ultrasound suspicion of fetal growth restriction (FGR). Adjusted risk ratios (aRRs) of perinatal outcomes were analysed. Results A total of 407 infants were included, comprising 268 (65.85%) with antenatal ultrasound suspicion of FGR. Antenatal suspicion of FGR was associated with increased risk of iatrogenic delivery (aRR 2.03, 95% confidence interval [CI] 1.31, 3.14) that included risk of preterm birth (aRR 10.61, 95% CI 1.35, 83.62) and elective caesarean section (aRR 1.306, 95% CI 1.051, 1.623). Differences in fetal death, 1-min Apgar score, and admission to neonatal intensive care unit were not statistically significant. Resuscitation risk was reduced (aRR 0.22, 95% CI 0.06, 0.79). Conclusions Regular use of third-trimester ultrasound in one teaching hospital in China showed satisfactory antenatal detection of FGR among SGA infants. Ultrasound suspicion of FGR was associated with higher incidence of iatrogenic deliveries, but not improved neonatal outcomes, except for reduced perinatal resuscitation.