产后出血是分娩期严重并发症，是孕产妇死亡的首要原因。由于诊断标准不同，各地报道的产后出血的发生率差异较大。产后出血的危险因素中宫缩乏力是引起产后出血的主要原因，但应注意每一个产妇都有发生产后出血的风险。近年来由于胎盘因素所致的难治性严重产后出血发生率有所增加，需要引起临床医生的重视。

Postpartum hemorrhage is an obstetrical emergency, and it is a major cause of maternal morbidity. Since the unified diagnostic criteria of postpartum hemorrhage is lacking, the incidence rate of postpartum hemorrhage varies widely in various regions. The most common cause of postpartum hemorrhage is uterine atony. Every pregnant woman has the possibility of postpartum hemorrhage. In recent years, the incidence of refractory severe postpartum hemorrhage caused by placenta disease is increasing, the clinicians should pay attention to it.