Antenatal corticosteroids and the influence of sex on morbidity and mortality of preterm infants.

Objective: To study the associated effect of a complete course of antenatal corticosteroids (ACSs) on mortality and morbidity rates among preterm infants in our population.

Study Design: Observational prospective study of infants born at less than 32 weeks' gestation and admitted to our Neonatal Care Unit between January 2012 and December 2018. We analyzed mortality at discharge and respiratory and neurological morbidity, both during hospitalization and at 24 months' postmenstrual age.

Results: The study included a total of 710 patients with a median gestational age of 28.5 weeks (IQR 26.4-30.5) and mean weight of 1.090 g (IQR 800-1.391). Of which, 62.4% received a complete course of antenatal steroids. Given the differences observed in the baseline characteristics of patients who either did or did not receive a full course of antenatal steroids, a propensity score covariate adjustment was performed for all estimations. The effect of ACS therapy differs depending on sex with a positive effect on acute respiratory morbidity and mortality in male patients of less than 29 weeks' gestation. In female infants, there is no significant beneficial association between ACS therapy and mortality or any of the morbidities studied.

Conclusion: In our population of preterm infants, treatment with antenatal steroids is associated with a different effect depending on sex. Antenatal steroids therapy associated with a positive effect in male patients with a gestational age of less than 29 weeks.