Late-Onset Severe Fetal Growth Restriction and Isolated Severely Small Abdominal Circumference: Do Neonatal Outcomes Differ? [ID: 1377666

Abstract

INTRODUCTION: Updated guidelines from the Society for Maternal-Fetal Medicine (SMFM) define severe fetal growth restriction (sFGR), or an estimated fetal weight (EFW) less than 3rd percentile, as a distinct entity due to higher perinatal morbidity in this group. Whether an isolated abdominal circumference (AC) less than 3rd percentile similarly portends adverse outcomes remains unclear. METHODS: This is a single-institution, retrospective cohort study of singleton gestations with late-onset FGR and normal Doppler studies from 2012 to 2022. Pregnancies affected by AC less than 3rd percentile (but EFW≥3rd percentile) and EFW less than 3rd percentile were compared using univariable analysis and multivariable logistic regression. The primary outcome was neonatal intensive care unit (NICU) admission. RESULTS: Among eligible participants, 78 (63%) had an isolated AC less than 3rd percentile and 45 (37%) had sFGR. Neonates prenatally diagnosed with sFGR were more likely to be admitted to the NICU than those with isolated AC less than 3rd percentile (68.9% versus 23.1%, P<.001). After adjusting for gestational age, birth weight, race, maternal age, and medical comorbidities, sFGR was still associated with an increased odds of NICU admission (adjusted odds ratio 4.9, 95% CI 1.37–17.48, P=.014). Rates of cesarean delivery (46.7% versus 26.9%; P=.03), small for gestational age (86.7% versus 67.9%, P=.02), and 5-minute Apgar score less than 7 (6.7% versus 0.0%, P=.02) were also higher in the sFGR group. There were no significant differences in NICU length of stay or perinatal death between groups. CONCLUSION: Adverse neonatal outcomes were more prevalent in pregnancies affected by sFGR compared with isolated AC less than 3rd percentile, providing support for the updated SMFM guidelines.