Risk factors for placenta previa in an Asian population.

OBJECTIVE: To identify the risk factors for placenta previa in an Asian population. METHODS: This retrospective cohort study involved Taiwanese women delivered between July 1990 and December 2003 at Chang Gung Memorial Hospital, Taipei, Taiwan. Pregnancies complicated by multiple gestation and fetal anomalies were excluded. RESULTS: There were 457 cases of placenta previa (1.2%) among the 37,702 pregnancies analyzed. Risk factors for placenta previa included a prior preterm birth (OR, 6.6; 95% confidence interval CI], 4.1-10.6); technology-assisted conception (OR, 4.8; 95% CI, 2.9-7.8); smoking (OR, 3.3; 95% CI, 1.2-9.1) or working (OR, 3.8; 95% CI, 2.8-5.3) during pregnancy; maternal age of, or greater than 35 years (OR, 2.0 to 2.2; 95% CI, 1.3-3.7); and previous induced abortions (OR, 1.3-3.0; 95% CI, 1.1-7.1). CONCLUSION: The risk factors for placenta previa were found to be the same for Asian women as those previously recorded for American and European women, but additional factors were detected.