The effect of sex on outcome of preterm infants - a population-based survey

Aim: To provide comprehensive data on potential sex differences in maternal and neonatal characteristics, short-term morbidity and neurodevelopmental outcome within an entire geographically determined collective of infants born at a gestational age <32 weeks. Methods: Between 2003 and 2008, we prospectively enrolled all infants born in Tyrol at <32 weeks of gestation; the association between sex, and a wide set of pre- and postnatal factors, post-discharge morbidity and neurodevelopmental outcome was analysed. Results: Girls less frequently suffered from early-onset sepsis than boys (p = 0.030). After adjustment for multiple corrections (Bonferronis p = 0.003), no sex differences were seen within any maternal or neonatal parameter. Analysis of morbidity revealed a higher readmission rate in boys (p < 0.0001), which was primarily caused by a greater incidence of respiratory problems (p = 0.003). Boys did not show a greater adverse neurodevelopmental outcome at the age of 12 or 24 months. Conclusion: Parents of boys should be prepared for a potentially higher frequency of readmission after initial discharge, but our data currently give no reason for parents of boys to be disproportionately anxious about their neurodevelopmental outcome. Whether boys also enjoy a rosy prognosis for developmental outcome at school age remains to be elucidated.