Racial and ethnic differences in the prevalence of placenta previa.

The objective of this study is to determine the prevalence of placenta previa among different racial and ethnic groups. We conducted a retrospective cohort study to examine the prevalence of placenta previa among five major racial and ethnic groups: African American, Asian, Caucasian, Hispanic and Native American. We included all deliveries ⩾20 weeks gestation from a large northern Californian Health Maintenance Organization from 1995–2006. A multivariable logistic regression model was used to control for potential confounders. Of the 394 083 deliveries in our cohort, 1580 (0.40%) were complicated by placenta previa. The prevalence of placenta previa was: Asian 0.64%, Native American 0.60%, African American 0.44%, Caucasian 0.36%, Hispanic 0.34% and unknown 0.31% (P<0.001). In our multivariable logistic regression model, only Asians (odds ratio (OR) 1.73, 95% confidence intervals (CI) 1.53–1.95) and African Americans (OR 1.43, 95% CI 1.19–1.72) were at increased risk for having placenta previa, compared with Caucasians. Asian women have the highest prevalence of placenta previa.