Purpose: The purpose of this retrospective cohort study was to elucidate whether the location of placenta below uterine incision in cesarean section is important in the development of maternal complications in placenta previa patients.Methods: The study was conducted on 409 patients 414 parturition at 3 hospitals in affiliation with the Catholic Medical Center, Seoul, Korea from May 1999 to December 2009. The subjects were divided to two groups: the group whose placenta was located in the anterior portion of the uterus (anterior group) and the group whose placenta was located in the posterior portion of the uterus (posterior group). And then they are compared to each other. Logistic regression was used to control for confounding factors.Results: In the anterior group, regardless of confounding factors, the incidence of excessive blood loss (OR 2.97; 95% CI: 1.64-5.37), massive transfusion (OR 3.31; 95% CI: 1.33-8.26), placental accreta (OR 2.60, 95% CI: 1.40-4.83), and hysterectomy (OR 3.47, 95% CI: 1.39-8.68) was higher.Conclusion: Sonographic determination of the placental position where its location beneath the uterine incision is very important to predict maternal outcomes in placenta previa patients, and such cases, close attention should be paid for massive hemorrhage.