ETIOLOGIC DETERMINANTS OF ABRUPTIO PLACENTAE

Objective: To quantify the roles of suspected sociodemographic, anthro pometric, behavioral, and pathologic determinants in the etiology of a bruptio placentae. Methods: We performed a hospital-based cohort study of 36,875 nonreferred births between January 1978 and March 1989. Ges tational 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 signi ficant independent associations with abruption. Significant determinan ts included the following: severe small for gestational-age (SGA) birt h (odds ratio [OR] 3.99; 95% confidence interval [CI] 2.75, 5.77), cho rioamnionitis (OR 2.50; 95% CI 1.58, 3.98), prolonged rupture of membr anes (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; 9 5% 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), unm arried 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 gend er (OR 1.38; 95% CI 1.12, 1.70). Removal of SGA from the regression mo del resulted in little change in the magnitude of the other associatio ns. Conclusions: Severe fetal growth restriction, prolonged rupture of membranes, chorioamnionitis, hypertension (before pregnancy and pregn ancy-induced), cigarette smoking, advanced maternal age, unmarried sta tus, and male fetal gender are significant etiologic determinants of p lacental abruption. Non-SGA determinants appear to operate largely ind ependently of their effects on fetal growth. Copyright (C) 1997 by The American College of Obstetricians and Gynecologists.