Male fetal sex is associated with earlier onset of placental abruption.

Placental abruption is an important cause of preterm birth, and perinatal morbidity and mortality. Although more common with male fetuses, outcomes have not been evaluated by sex. Our aim was to find out whether short-term morbidity differs by infant sex in cases with placental abruption and in controls.Register-based case-control study.National Hospital Discharge Register and Medical Birth Register data 1987-2005.The study population consisted of 4,081 women with placental abruption and singleton infant. Three control women without placental abruption were selected for each case matched by maternal age, parity, year of birth, and hospital district. A total of 3,688 cases and 12,695 controls had liveborn infants.Data on pregnancy, delivery, and perinatal outcomes were collected.Placental abruption.The sex ratio (proportion of male) of cases was 0.548 and of controls 0.516 (p = 0.001). Compared with females, male fetuses in the placental abruption group were born earlier (p = 0.018). Compared with controls, cases with placental abruption were born earlier (p < 0.001), had lower birthweight (p < 0.001), were more often growth restricted (p < 0.001), had lower Apgar scores (p < 0.001) and pH (p < 0.001). Newborn cases needed special care, respirator treatment, antimicrobial and phototherapy more often (p < 0.001) than controls. There was no difference in perinatal outcomes between female and male infants in the placental abruption group.Placental abruption occurred earlier in pregnancy with male fetal sex but otherwise the outcomes were similar. Compared with controls newborns in the placental abruption group had a worse outcome.