- To investigate risk factors and pregnancy outcome of patients with placental abruption. A population-based study comparing all pregnancies of women with and without placental abruption was conducted. Stratified analysis using multiple logistic regression models was performed to control for confounders. During the study period there were 185,476 deliveries, of which 0.7% (1365) occurred in patients with placental abruption. The incidence of placental abruption increased between the years 1998 to 2006 from 0.6 to 0.8%. Placental abruption was more common at earlier gestational age. The following conditions were significantly associated with placental abruption, using a multivariable analysis with backward elimination: hypertensive disorders, prior cesarean section, maternal age, and gestational age. Placental abruption was significantly associated with adverse perinatal outcomes such as Apgar scores < 7 at 1 and 5 min and perinatal mortality. Patients with placental abruption were more likely to have cesarean deliveries, as well as cesarean hysterectomy.Using another multivariate analysis, with perinatal mortality as the outcome variable, controlling for gestational age, hypertensive disorders, etc., placental abruption was noted as an independent risk factor for perinatal mortality. Placental abruption is an independent risk factor for perinatal mortality. Since the incidence of placental abruption has increased during the last decade, risk factors should be carefully evaluated in an attempt to improve surveillance and outcome.