After 20 weeks of pregnancy or during delivery, the normally located placenta partially or completely detaches from the uterine wall before the fetus is delivered. This is called placental abruption. Placental abruption is a serious complication in late pregnancy. It has an acute onset and rapid progression. If not treated in time, it can endanger the lives of mother and child. The incidence reported in China is 4.6‰~21‰, and the incidence reported abroad is 5.1‰~23.3‰. The incidence rate is related to whether the placenta is carefully examined after delivery. Some mild placental abruption may have no obvious symptoms before delivery. Only when the placenta is examined after delivery, blood clots are found at the abruption site. Such patients are easily overlooked.