Sex differences in the outcome of very low birth weight premature infants born in a regional Australian Neonatal Intensive Care Unit

Abstract

Background: Advancements in neonatal care have improved survival for premature and very low birth weight (VLBW) infants. Despite this, differences have been reported when comparing males and females. While the previously described concept of the “male disadvantage” asserts that there is a higher risk of mortality and morbidity for male infants, many studies have also found no sex differences in outcomes.

Aim: The objective of this study is to determine if the sex of VLBW premature infants is associated with survival and neurodevelopmental outcome in a regional Australian Neonatal Intensive Care Unit (NICU).

Methods: A retrospective cohort study was conducted for infants born at < 37 weeks gestation with VLBW (< 1,500 g) admitted to The Townsville Hospital NICU between 2010 and 2015. Comparisons for survival and neurodevelopment between males and females were made with Chi-square, Fisher’s exact test and the Independent t-test. Multivariate logistic regression analysis was performed for the outcomes of death before NICU discharge and developmental delay assessed by the Bayley Scales of Infant and Toddler Development, the 3^rd Edition.

Results: Data were collected for 430 infants. Fifty-three infants died before NICU discharge, with no sex difference in survival. Follow-up assessment was completed for 84 infants from the original cohort and demonstrated no sex differences in neurodevelopmental outcome. Male infants had a significantly higher prevalence of chronic lung disease (p = 0.009). Neither the logistic regression model for death by NICU discharge nor for neurodevelopmental delay identified sex as a significant predictor of outcome.

Conclusions: Male and female VLBW premature infants did not differ in survival or neurodevelopmental outcome at this center.