목적: To describe the incidence of placenta previa in nulliparous women and to assess risk factors between nulliparous and multiparous women with placenta previa after adjustment for pervious dilatation and curettage, in vitro fertilization (IVF), smoking, previous cesarean section and maternal age. 방법: A retrospective study was conducted based on the descriptive and statistical analysis risk factors of placenta previa and maternal and fetal prognosis of 221 patients who underwent cesarean section for placenta previa between January 2010 and December 2015 in Busan Paik hospital. We divided the patients into two groups, nulliparous women and multiparous women, and compared with cause of previa and prognosis. 결과: 106 patients (48.0%) was nulliparous women and 115 patients(52.0%) was mutiparous women. Placenta previa totalis was the most common type of previa but there was no significant difference between nulliparous women and multiparous women(43.9% vs 56.1%). Nulliparous women were younger than multiparous women(32.6±3.4 years old vs 34.5±4.5 years old, p=0.0005). Placental previa with risk factors was occurred in 141 patients( 63.8%) and the others, 80 patients(36.2%) showed placenta previa without risk factors. It was presented that no risk factor in nulliparous women was significantly many compared with multiparous women(61.2% vs 38.8%, p=0.0045). In the multiple logistic regression analysis the strongest independent risk factor of placenta previa was IVF between nulliparous and multiparous women(78.1% vs 21.9%, p=0.0003). There was no significant difference in the incidence of postpartum hemorrhage(PPH) but was significantly different in management. Cesarean hysterectomy for PPH was significantly increased in multiparous women(80.0% vs 20.0%, p=0.0352). 결론: Increasing maternal age and in vitro fertilization(IVF) treatment are all risk factors for placenta previa in nulliparous women in this study. Therefore the strategies to prevent placental previa in nulliparous women undergoing IVF are needed.