Background: Placenta previa (PP) can cause repeated and catastrophic bleeding that may lead to increased maternal and neonatal mortality and morbidity. The purposes of this study were to determine the relationship between antepartum hemorrhage (APH) and gestational week, the frequency of APH, the risk factors for APH, and whether patients with APH developed more severe adverse perinatal outcomes. Methods: This was a multi-center, retrospective study in which we enrolled all placenta previa patients between October 2015 and September 2018 within the Partners Healthcare System. Results: The mean APH frequency was 2.2 \pm 1.3 in women with PP, with the majority having experienced a one-time bleeding episode (36.4%, 44/121). The incidence of APH varied from 2.6% to 14.6% in every gestational week, with the highest incidence at 32 gestational weeks. Complete placenta was an independent risk factor for APH (odds ratios, 4.17; 95% confidence intervals, 1.805–9.634). Pregnant women with APH underwent more emergent cesarean deliveries (54.5%, p 0.05), and more newborns manifested respiratory distress syndrome (34.7%, p 0.05). Conclusions: The APH morbidity varied by gestational week, with the 32nd gestational week appearing to have the highest incidence of PP. Complete PP can cause more frequent APH, and PP plus APH may increase maternal and neonatal adverse outcomes.