Cigarettes, coffee, and preterm premature rupture of the membranes.

Premature (prior to 37 completed weeks of gestation) rupture of the membranes (preterm PROM) is one of the most common underlying causes of preterm delivery. However, there have been few epidemiologic studies of this obstetric complication. The authors studied the relation of maternal cigarette smoking and coffee consumption to both preterm PROM and spontaneous preterm labor not complicated by premature rupture of the membranes (preterm NONPROM) in a large cross-sectional data base. The 307 preterm PROM and 488 preterm NONPROM cases who delivered during 1977-1980 at the Boston Hospital for Women were compared with 2,252 randomly selected women who delivered at term at that institution. Multiple logistic regression techniques were used to derive maximum likelihood estimates of adjusted odds ratios (OR) and 95% confidence intervals (CI). After confounders had been adjusted for, the relative risk of preterm PROM for women who reported ever having smoked during pregnancy, as compared with nonsmokers, was 1.6 (95% CI 1.1-2.4). However, no gradient between the number of cigarettes smoked per day and the risk of preterm PROM was observed. Similar results were observed for preterm NONPROM. Women who consumed three or more cups of coffee daily during the first trimester had a 2.2-fold greater risk of preterm PROM than did women who drank two or fewer cups (95% CI 1.5-3.3). Among coffee drinkers, there was some evidence of a linear trend in the risk of preterm PROM as coffee consumption increased. Consumption of three or more cups of coffee per day was less strongly associated with the occurrence of preterm NONPROM (adjusted OR = 1.4, 95% CI 1.0-1.9).