Birth outcomes and survival by sex among newborns and children under 2 in the Birhan Cohort: a prospective cohort study in the Amhara Region of Ethiopia.

Introduction: Despite the progress in reducing child mortality, the rate remains high, particularly in sub-Saharan African countries. Limited data exist on child survival and other birth outcomes by sex. This study compared survival rates and birth outcomes by sex among neonates and children under 2 in Ethiopia.

Methods: Women who gave birth after 28 weeks of gestation and their newborns were included in the analysis. Survival probabilities were estimated for males and females in the neonatal period as well as the 2-year period following birth using Kaplan-Meier curves. HRs and 95% CIs were compared between males and females under 2. Descriptive statistics and χ² tests were used to determine the sex-disaggregated variation in the birth outcomes of preterm birth, low birth weight (LBW), stillbirth, small for gestational age (SGA) and large for gestational age (LGA).

Results: The study included a total of 3904 women and child pairs. The neonatal mortality rate for males (3.4%, 95% CI 2.6% to 4.2%) was higher compared with females (1.7%, 95% CI 1.1% to 2.3%). The hazard of death during the first 28 days of life was approximately two times higher for males compared with females (HR 1.99, 95% CI 1.30 to 3.06) but was not significantly different after this period. While there was a non-significant difference between males and females in the proportion of preterm, LBW and LGA births, we found a significantly higher proportion of stillbirth (2.7% vs 1.3%, p=0.003) and SGA (20.5% vs 15.6%, p<0.001) for males compared with females.

Conclusions: This study identified a significant sex difference in mortality and birth outcomes. We recommend focusing future research on the mechanisms of these sex differences in order to better design intervention programmes to reduce disparities and improve outcomes for neonates.