Risk factors for abruptio placentae.

The authors studied the relation of sociodemographic, medical, and life-style factors and abruptio placentae in a large cross-sectional data base. The 143 cases of abruption identified in the Delivery Interview Program, conducted in Boston from 1977 to 1980, were compared with 1,257 randomly selected controls. The authors used multiple logistic regression techniques to derive maximum likelihood estimates of the adjusted odds ratios and 95% confidence intervals as measures of the association between exposure factors and abruption. A history of chronic hypertension was associated with a threefold increase in risk (odds ratio (OR) = 3.1, 95% confidence interval (Cl) 1.1-8.4), but pregnancy-induced hypertension was not associated with abruption. Excess risk was associated with advanced maternal age (OR = 2.3, 95% Cl 1.3-3.9), low prepregnancy body mass index (OR = 2.3, 95% Cl 1.3-4.1), a history of prior stillbirth (OR = 3.5, 95% Cl 1.8-7.0), and at least weekly use of marijuana during pregnancy (OR = 2.8, 95% Cl 1.2-6.6). Overall, the association with cigarette smoking during pregnancy was of only borderline significance (OR = 1.5, 95% Cl 1.0-2.2), although there appeared to be a dose-response relation between the number of cigarettes smoked and risk of abruption.