If the placenta reaches the endocervix before the 28th week of pregnancy, in most cases, due to the gradual increase of the uterus, the placenta will slowly move up and can return to its normal position. However, if the placenta is still at the endocervix after 28 weeks of pregnancy, the placenta is low or placenta praevia, which may cause hemorrhage in late pregnancy and may also obstruct the descent of the fetal head during delivery, and most of them need to be delivered by cesarean section. During cesarean delivery, there is sometimes hemorrhage because the placenta is attached to the lower part of the uterus.