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

OBJECTIVE: This study examined the relationship between two maternal e xposures, cigarette smoking and cocaine use, and placenta previa. STUD Y DESIGN: A hospital-based case-control study was conducted. Three hun dred four cases of placenta previa were compared with 2732 controls wi th respect to demographic characteristics, substance use, and perinata l characteristics. Logistic regression was used to examine the individ ual effects of cigarette smoking and cocaine use on placenta previa, i ndependent of other known risk factors. RESULTS: A dose-response relat ionship between smoking cigarettes and placenta previa was observed in dependent of other known risk factors (p(trend) < 0.01). Pregnant wome n who smoked greater-than-or-equal-to 20 cigarettes per day were over two times more likely to experience a placenta previa relative to nons mokers (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. CONCLUSION S: The previously observed association between smoking and placenta pr evia is supported by the dose-response relationship observed in this s tudy. The potential association of cocaine with placenta previa needs more exploration.