Effects of Fetal Gender on Occurrence of Placental Abruption

A multicenter retrospective cohort study was conducted to clarify the differences in occurrence of placental abruption between placenta with and without the Y chromosome. We reviewed the chart records from the database of the Japan Perinatal Registry Network during the period from January to December 2009. 348 women were included. Risk factors were compared to those of pregnant women with a female fetus. The fetal sex ratio was 1.22: 191 male cases and 157 female cases. There were no significant differences in maternal background factors, perinatal or neonatal and infantile outcomes between the two groups. In terms of risk factors, pregnant women with a male fetus had a significantly lower incidence (30/191, 15.7%) of pregnancy-induced hypertension as compared with female fetuses (44/157, 28.0%, p = 0.0052) (relative risk: 0.48 [95% confidence intervals: 0.29-0.80]). Placental abruption occurred in pregnancies with a male fetus even in the absence of reported risk factors for placental abruption.