Impact of gestational hypertension and preeclampsia on fetal gender: A large prospective cohort study in China.

BACKGROUND

Recent studies suggested an association between fetal sex preponderance and hypertensive disorders during pregnancy, but the conclusions were inconsistent. Our objective was to investigate whether the occurrence of gestational hypertensive disorders would affect the possibility of delivering boys.

METHODS

Data were obtained from the China-US Collaborative Project for Neural Tube Defects Prevention, a large population-based cohort study. We included participants who were registered in 2 southern Chinese provinces, and whose information of blood pressure and sex delivery were recorded in detailed. Blood pressure was measured during pregnancy by trained health care workers and other health-related information was recorded prospectively. We used log-binomial regression to evaluate the association between gestational hypertension or preeclampsia and the chance of male delivery.

RESULTS

Among 205,605 singleton pregnancy women, the overall incidences of gestational hypertension and preeclampsia were 9.5% and 2.4%, respectively. The prevalence of male delivery was 51.1% and 50.2% in the groups of gestational hypertension and preeclampsia, while in the normotension group was 52.0%. After adjustment for the effects of the main potential confounders, women with gestational hypertension and preeclampsia both showed significantly decreased probability of giving birth to a boy. The adjusted risk ratios (RRs) were 0.98 (95% confidence interval (CI): 0.97-0.99) and 0.96 (95% CI: 0.94-0.99), respectively.

CONCLUSIONS

Our results support a slight but significant association between gestational hypertension or preeclampsia and decreased likelihood of male delivery.