130 Twin birthweight discordance and adverse neonatal outcomes

Abstract

The impact of intertwin birthweight discordance on neonatal outcomes remains unclear. We compared adverse neonatal outcomes between concordant and discordant twins, controlling for fetal growth and chorionicity. Retrospective cohort study of twins categorized as small, appropriate, and large for gestational age (SGA 90%ile respectively), using a twin-specific US nomogram stratified by chorionicity (Anath et al). Discordance was analyzed at 15% and 20% cutoffs in two groups: 24 0/7-33 6/7 and 34 0/7-38 6/7 weeks. Pre-specified composite primary neonatal outcome included respiratory distress syndrome requiring mechanical ventilation, 5-min Apgar <4, intraventricular hemorrhage (IVH) grade III or IV, necrotizing enterocolitis, neonatal sepsis, neonatal intensive care unit (NICU) admission >1 week, and neonatal death. Composite secondary neonatal outcome included IVH grade I-II, transient tachypnea, hypoglycemia, hyperbilirubinemia, and NICU admission ≤1 week. Outcomes were compared between concordant and discordant twins and adjusted for potential confounders including chorionicity, SGA, hypertensive disorders, antenatal steroids, gestational age at delivery, and delivery mode. 1213 twin sets were analyzed. In unadjusted analyses, both primary and secondary outcomes were significantly greater at both ≥15% and ≥20% discordance in both gestational age groups (all p<.05). In the adjusted models, primary outcome was still significantly greater at both ≥15% and ≥20% discordance at 24 0/7-33 6/7, but not at 34 0/7-38 6/7 weeks (Table). Neither degree of discordance was significantly associated with the secondary outcome in either gestational age group in the adjusted analyses (Table). In twins born at <34 0/7 weeks, intertwin birthweight discordance ≥15% was significantly associated with increased odds of adverse primary, but not secondary, neonatal outcomes, even when controlled for chorionicity and SGA status. Degree of discordance was not associated with adverse neonatal outcomes with delivery at later gestational ages.