Vaginal bleeding of more than 500 ml within 24 hours after vaginal delivery and more than 1,000 ml in case of cesarean section is considered early postpartum hemorrhage, which is currently the first cause of maternal mortality in China. And heavy uterine bleeding that occurs after 24 hours after delivery is called late postpartum hemorrhage. Early postpartum hemorrhage is mainly caused by four major reasons: weak contractions, placental factors, soft birth canal injury and coagulation disorders. Weakness of uterine contraction can be caused by excessive fatigue during labor, not eating and resting well, which leads to prolonged labor and weak uterine contraction; it can also be caused by oversized fetus, excessive amniotic fluid, twin pregnancy, uterine fibroids, uterine developmental deformity, etc., which leads to weak uterine contraction; or excessive application of sedative and analgesic drugs during labor, which leads to weak uterine contraction. Placental factors are mostly caused by the retention of placenta after delivery, which is not delivered within 15 minutes as early as possible, or there is adhesion or implantation of the placenta, and residual placenta, which leads to hemorrhage in the postpartum period. Postpartum hemorrhage occurs when the fetus is too big during delivery, or when the delivery is too fast, or when there is a laceration of the perineum or cervix caused by surgical assisted delivery. Thrombocytopenia during pregnancy, abnormalities of liver function or coexisting liver diseases, and complications of pregnancy such as placenta previa, amniotic fluid embolism, severe preeclampsia, stillbirth, etc., can increase the risk of postpartum hemorrhage due to coagulation dysfunction. The main causes of late postpartum hemorrhage are: residual placenta membranes, poor recovery of uteroplacental attachment wounds, infection of the uterus, or poor healing of the uterine incision after cesarean section. Postpartum hemorrhage can be prevented by reducing abortion and scraping, controlling weight gain during pregnancy, controlling the size of the fetus, actively treating complications during pregnancy, and preventing and treating anemia; and making a good delivery plan for mothers with high-risk factors for postpartum hemorrhage, actively preventing and treating serious postpartum hemorrhage and maximizing the safety of mothers and babies.