The causes of hemorrhage in normal labor: a. weak contraction of the uterus, a large part of the postpartum bleeding is due to weak contraction of the uterus, if the contraction of the uterus is not good at this time, it is likely to hemorrhage. If the wound is deep in the vagina or uterus, it will not be good to stop bleeding and the probability of hemorrhage will increase. The placenta is partially stored in the body, after the birth, if the placenta still remains in the uterus, there will be hemorrhage, the doctor will use manual stripping placenta, but the probability of hemorrhage is still there. Fourth, the coagulation machine turn abnormal, some women may be born with abnormal coagulation function, will also directly lead to the probability of postpartum hemorrhage increased, if there are abnormal coagulation function of the mother, you need to explain the situation in advance.