Abstract
We studied the telation between sociodemographic, medical, and life-style factors and preterm (prior to 37 completed weeks of gestation) premature rupture of the membranes (preterm PROM) in a large cross-sectional data base. The 307 preterm PROM cases and 488 spontaneous preterm deliveries not complicated by premature rupture of the membranes (preterm NONPROM) were compared with 2,252 randomly selected term controls. Using multiple logistic regression, we derived maximum likelihood estimates of adjusted odds ratios (OR) and 95% confidence intervals (CI). Excess risk of preterm PROM was associated with primiparity (OR = 1.6, 95% CI 1.2-2.1), low educational attainment (OR = 2.3, 95% CI 1.7-3.1), in utero exposure to diethylstilbestrol (OR = 2.3, 95% CI 1.1-4.8), a history of prior stillbirth (OR = 2.0, 95% CI 1.0-4.4), cervical incompetence (OR = 6.5, 95% CI 3.4-12.6), and antepartum hemorrhage (OR = 3.8, 95% CI 2.9-5.0). Black race was associated with a 1.7-fold increased risk of preterm NONPROM (OR = 1.7, 95% CI 1.3-2.3), but was not associated with preterm PROM (OR = 0.8, 95% CI 0.6-1.2). Other statistically significant risk factors for preterm NONPROM included low prepregnancy body mass index (OR = 1.6, 95% CI 1.1-2.3), and late registration for prenatal care (OR = 1.4, 95% CI 1.0-1.9). These results underscore the potential for heterogeneity and complexity in the etiology of shortened gestations.