(407) Is timing of onset of early fetal growth restriction associated with worse outcomes?

Objective: Fetal growth restriction (FGR) is associated with significant neonatal morbidity and mortality, which can especially be impacted by timing of onset. Limited data are available to assess whether timing of diagnosis among the high-risk cohort of early-onset FGR (i.e., diagnosis at < 32 weeks) is associated with adverse outcomes.

Study Design: We conducted a single-site retrospective study of singleton gestations with early-onset FGR, diagnosed between 2020-2023. The exposure was gestational age (GA) at time of diagnosis, dichotomized into 20-27 weeks (group 1) and 28-31 weeks (group 2). The primary outcome was a composite of adverse neonatal outcomes (i.e., neonatal intensive care unit admission, respiratory distress syndrome, need for intubation, sepsis, necrotizing enterocolitis, intraventricular hemorrhage, periventricular leukomalacia, retinopathy of prematurity, death). Secondary outcomes were GA at delivery, route of delivery, diagnosis of small-for-gestational age, neonatal length of stay, and all components of the primary outcome. Bi- and multivariate analyses were performed.

Results: 94 participants were eligible; 52% (n=49) were in group 1 and 48% (n=45) were in group 2. Individuals with earlier onset of FGR were more likely to have public payor insurance, be nulliparous and have hypertensive disorders (Table 1). The frequency of the composite outcome was not significantly different between the two groups (45 v. 29%, RR 1.55, 95% CI 0.89-2.70), even after controlling for receipt of antenatal steroids (aRR 1.29, 95% CI 0.82-2.04). Furthermore, there were no differences in any of the secondary outcomes (Table 2).

Conclusion: GA at diagnosis of early-onset FGR is not associated with worse maternal or perinatal outcomes, though the directionality of the findings warrants further investigation with a larger sample size.