Objective: Our aim was to determine whether maternal cocaine exposure is a risk factor for placenta previa.
Study design: In this case-control study, cases of placenta previa confirmed at delivery (ascertained by International Classification of Diseases, ninth revision, Clinical Modification, code-based search, N = 40) were compared with a random sample of patients without placenta previa (N = 80) in a ratio of two controls per case. Data on antecedent maternal cocaine use, as well as other potential risk factors for placenta previa, were obtained from a review of the prenatal chart and the hospital record. Categorization of cocaine use was based on either patient self-report or urine toxicologic testing, or both. Multiple logistic regression was performed to assess the association between cocaine and placenta previa while we controlled for other variables.
Results: After the effects of other variables were adjusted for, maternal cocaine use was an independent risk factor for placenta previa (adjusted odds ratio = 4.39, 95% confidence interval 1.17 to 16.4). Other significant risk factors included a history of cesarean section and prior elective abortion.
Conclusion: These results suggest that cocaine use, as well as prior cesarean section, prior elective abortion, and parity, are associated with placenta previa.