Objective: To quantify the roles of suspected sociodemographic, anthropometric, behavioral, and pathologic determinants in the etiology of abruptio placentae.
Methods: We performed a hospital-based cohort study of 36,875 nonreferred births between January 1978 and March 1989. Gestational age was based on menstrual dates confirmed (within 7 days) by early ultrasound.
Results: Parity, maternal education, pre-pregnancy weight, and the rate of net gestational weight gain did not have significant independent associations with abruption. Significant determinants included the following: severe small for gestational-age (SGA) birth (odds ratio [OR] 3.99; 95% confidence interval [CI] 2.75, 5.77), chorioamnionitis (OR 2.50; 95% CI 1.58, 3.98), prolonged rupture of membranes (OR 2.38; 95% CI 1.55, 3.65), preeclampsia (OR 2.05; 95% CI 1.39, 3.04), pregnancy-induced hypertension without albuminuria (OR 1.57; 95% CI 1.00, 2.46), pre-pregnancy hypertension (OR 1.77; 95% CI 1.05, 2.99), maternal age at least 35 years (OR 1.50; 95% CI 1.14, 2.01), unmarried status (OR 1.50; 95% CI 1.13, 1.98), cigarette smoking (OR 1.40; 95% CI 1.00, 1.97 for ten to 19 cigarettes per day and OR 1.13; 95% CI 0.81, 1.59 for at least 20 cigarettes per day), and male fetal gender (OR 1.38; 95% CI 1.12, 1.70). Removal of SGA from the regression model resulted in little change in the magnitude of the other associations.
Conclusions: Severe fetal growth restriction, prolonged rupture of membranes, chorioamnionitis, hypertension (before pregnancy and pregnancy-induced), cigarette smoking, advanced maternal age, unmarried status, and male fetal gender are significant etiologic determinants of placental abruption. Non-SGA determinants appear to operate largely independently of their effects on fetal growth.