The impact of fetal gender on preterm birth in a southern Chinese population

OBJECTIVE: This study was conducted to determine whether carrying a singleton male fetus increases the risk of preterm birth (PTB) in Chinese women. METHODS: A retrospective cohort study was conducted on women with singleton pregnancies and delivered in our hospital. Maternal characteristics, pregnancy outcome, and incidence of PTB, were compared between women carrying a male versus a female fetus. The independent effect of a male fetus on PTB was examined with multiple logistic regression analysis adjusting for the other confounding factors identified. RESULTS: There were significant differences in maternal and infant characteristics between women with a male versus a female fetus. Despite similar or lower incidences of complications and labor induction, women with a male fetus had increased birth <37 weeks (7.0% versus 6.2%, p<?0.001) and birth at 34?36 weeks (5.15% versus 4.4%, p<0.001), but not for birth <34 weeks (2.0% versus 1.8%, p=?0.163). Regression analysis confirmed the association between male fetus with birth at 34-36 weeks (aOR 1.11, 95% CI 1.10?1.33) and spontaneous preterm labor (aOR 1.09, 95% CI 1.00-1.19). CONCLUSIONS: The results confirmed that carrying a male fetus is an independent risk factor for spontaneous preterm labor and PTB at 34?36 weeks gestation in southern Chinese women.