OBJECTIVE

To report our 10-year experience of protocol-based management of small-for-gestational-age (SGA) fetuses, based on standardized clinical and Doppler criteria, in late-pregnancy cases.

METHODS

A retrospective cohort was constructed of consecutive singleton pregnancies referred for late-onset (> 32 weeks) SGA (defined as estimated fetal weight (EFW) < 10 centile) that were classified as fetal growth restriction (FGR) or low-risk SGA, based on the severity of smallness (EFW < 3 centile) and the presence of Doppler abnormalities (uterine artery pulsatility index (UtA-PI) ≥ 95 centile or cerebroplacental ratio (CPR) < 5 centile). Low-risk SGA pregnancies were followed at 2-week intervals and delivered electively at 40 weeks. FGR pregnancies were followed at 1-week intervals, or more frequently if there were signs of fetal deterioration, and were delivered electively after 37 + 0 weeks' gestation. The occurrence of stillbirth and composite adverse outcome (CAO; defined as neonatal death, metabolic acidosis, need for endotracheal intubation or need for admission to the neonatal intensive care unit) was analyzed in low-risk SGA and FGR pregnancies.

RESULTS

A total of 1197 pregnancies with EFW < 10 centile were identified and classified at diagnosis as low-risk SGA (n = 619; 51.7%) or FGR (n = 578; 48.3%). Of these, 160 were delivered before 37 weeks' gestation; for obstetric reasons in 93 (58.1%) cases, severe pre-eclampsia in 33 (20.6%), FGR with severe hypoxia in 47 (29.4%) and stillbirth in four (2.5%) (indications are non-exclusive). During follow-up, 52/574 (9.1%) low-risk SGA pregnancies were reclassified as FGR, whereas 22/463 (4.8%) FGR pregnancies were reclassified as low-risk SGA. Overall, there were no stillbirths in the low-risk SGA group and four in the FGR group, all of which occurred before 37 weeks. There were no instances of neonatal death in pregnancies delivered ≥ 37 weeks. The risk of CAO was higher in those meeting antenatal criteria for FGR at 37 weeks than in those classified as low-risk SGA (32/493 (6.5%) vs 15/544 (2.8%); odds ratio, 2.5 (95% CI, 1.3-4.6)). In FGR pregnancies, the adjusted odds ratio (95% CI) for CAO was 6.3 (1.8-21.1) in those with EFW < 3 centile, while it was 3.2 (1.5-6.8) and 4.2 (1.9-8.9) in those with UtA-PI ≥ 95 centile and CPR < 5 centile, respectively, as compared to FGR pregnancies without each of these criteria.

CONCLUSION

Protocol-based risk stratification with different management and monitoring schemes for late pregnancy with a suspected SGA baby, based on clinical and Doppler criteria, enables identification and tailored assessment of high-risk FGR, while allowing expectant management with safe perinatal outcome for low-risk SGA fetuses. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.