Sex-specific relationships between early nutrition and neurodevelopment in preterm infants

Background Although early nutrition is associated with neurodevelopmental outcome at 2 years' corrected age in children born very preterm, it is not clear if these associations are different in girls and boys. Methods Retrospective cohort study of infants born <30 weeks' gestational age or <1500 g birth weight in Auckland, NZ. Macronutrient, energy and fluid volumes per kg per day were calculated from daily nutritional intakes and averaged over days 1-7 (week 1) and 1-28 (month 1). Primary outcome was survival without neurodevelopmental impairment at 2 years corrected age. Results More girls (215/478) survived without neurodevelopmental impairment at 2 years (82% vs. 72%, P = 0.02). Overall, survival without neurodevelopmental impairment was positively associated with more energy, fat, and enteral feeds in week 1, and more energy and enteral feeds in month 1 (P = 0.005-0.03), but all with sex interactions (P = 0.008-0.02). In girls but not boys, survival without neurodevelopmental impairment was positively associated with week 1 total intakes of fat (OR(95% CI) for highest vs. lowest intake quartile 62.6(6.6-1618.1), P < 0.001), energy (22.9(2.6-542.0), P = 0.03) and enteral feeds (1.9 x 10(9)(9.5-not estimable), P < 0.001). Conclusions Higher early fat and enteral feed intakes are associated with improved outcome in girls, but not boys. Future research should determine sex-specific neonatal nutritional requirements.