Postpartum hemorrhage refers to heavy bleeding that is difficult to stop after childbirth. It is a very serious but uncommon complication. If treated promptly, it will not be life-threatening. Bleeding may occur if the uterus is too relaxed or fails to contract due to long and exhausting labor, or if the birth wound is too large. Excessive uterine expansion may be caused by multiple births, large fetuses, polyhydramnios, and maternal weakness (such as anemia, fright, or excessive fatigue). Placental malformations can also prevent the uterus from contracting symmetrically. Globally, postpartum hemorrhage remains the most common cause of maternal death. Effective control of postpartum hemorrhage can avoid many unnecessary deaths of pregnant women. Postpartum hemorrhage occurs in any place of delivery, and 70% of postpartum hemorrhage is caused by uterine atony. In addition to the use of uterotonics and uterine massage, other methods for treating uterine atony seem to require further surgical intervention, which may have required a lot of complex medical equipment in the past, but this is unlikely in remote areas, affecting further intervention, which may become a cause of maternal death. Bleeding immediately after delivery can also occur if there is damage to the uterus, cervix, vagina, or pelvis that has not healed, or if the uterus has ruptured or is inverted (with the inside facing out). Bleeding can occur within a week or two after delivery if pieces of the placenta remain in the uterus or are stuck to the uterus. Infections and use of aspirin, ibuprofen, ginkgo biloba, high-dose vitamin E, marijuana, or other drugs that affect blood clotting can also cause bleeding after delivery, usually in the delivery room or a few weeks later. Bleeding is more likely to occur in women with ectopic pregnancies or premature births and is less likely to be caused by a known genetic predisposition to a blood disorder.