Role of sex in morbidity and mortality of very premature neonates

BACKGROUND: The aim of this study was to investigate the effect of sex on survival and short-term outcomes of very low-birthweight infants (VLBWI) born in Japan. METHODS: This study included VLBWI who were admitted to neonatal intensive care units participating in the Neonatal Research Network of Japan, between 2003 and 2012. The primary outcome was a composite of mortality or any major morbidity, including neurologic injury, bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), or retinopathy of prematurity requiring treatment. RESULTS: The composite primary outcome was worse in male infants. Male infants were also more likely to develop BPD. This difference reached statistical significance in neonates born at ≥26 weeks of gestation. In contrast, significant difference in the incidence of NEC was more likely to be seen at 23-25 weeks of gestation. CONCLUSION: Male neonates are more likely to die and are at a higher risk of respiratory and gastrointestinal complications than female neonates.