THE RELATIONSHIP BETWEEN EXPOSURE DURING PREGNANCY TO CIGARETTE-SMOKING AND COCAINE USE AND PLACENTA-PREVIA

OBJECTIVE: This study examined the relationship between two maternal exposures, cigarette smoking and cocaine use, and placenta previa. STUDY DESIGN: A hospital-based case-control study was conducted. Three hundred four cases of placenta previa were compared with 2732 controls with respect to demographic characteristics, substance use, and perinatal characteristics. Logistic regression was used to examine the individual effects of cigarette smoking and cocaine use on placenta previa, independent of other known risk factors. RESULTS: A dose-response relationship between smoking cigarettes and placenta previa was observed independent of other known risk factors (p(trend) < 0.01). Pregnant women who smoked greater-than-or-equal-to 20 cigarettes per day were over two times more likely to experience a placenta previa relative to nonsmokers (odds ratio 2.3, 95% confidence interval 1.5 to 3.5). Pregnant women who used cocaine were 1.4 times (95% confidence interval 0.8 to 2.4) as likely to experience a placenta previa as nonusers. CONCLUSIONS: The previously observed association between smoking and placenta previa is supported by the dose-response relationship observed in this study. The potential association of cocaine with placenta previa needs more exploration.