Maternal and Neonatal Characteristics and Sex Ratios in Humans

Abstract

PURPOSE: To understand the correlation of sex ratio at birth and maternal health and social characteristics, and neonatal characteristics. METHODS: We obtained data from the state of Massachusetts and analyzed births that occurred in the state and births that occurred to the residents of the state from 1987-2015 with about 80,000 births per year in each set. We analyzed categories such as the mothers’ marital status, hypertension (chronic and gestational), diabetes (chronic and gestational), Apgar scores at 1 and 5 minutes, and birthweight of the offspring. RESULTS: We found a higher sex ratio correlated with a higher birthweight (p <0.001). Higher sex ratio at birth also correlated with lower Apgar scores at 1 and 5 minutes (p <.001). Higher sex ratio was correlated with diabetes (gestational and chronic, p = 0.04495) in births occurring in MA, but no association was found in births to MA residents. Higher sex ratio was also found in gestational diabetes (p = 0.01151). There was no correlation between sex ratio at birth and chronic hypertension, but a higher sex ratio was found to be associated with gestational hypertension. Marital status of the mother did not show any association with sex ratio at birth. CONCLUSIONS: Maternal health is correlated with sex ratio at birth with higher sex ratio associated with gestational diabetes, and gestational hypertension. Higher sex ratio is also correlated with neonatal qualities such as higher birthweights and lower Apgar scores. These results suggest that male offspring may be associated with increased risks to the mother during pregnancy and intrapartum period. However, it is unclear how these findings correlate to the widely known Trivers-Willard hypothesis, suggesting the necessity for further research.