Whether or not the lower edge of the placenta covering the inside of the cervix will go up depends on the week of pregnancy and the specific circumstances of the woman. Generally, it is possible for the placenta to grow back before the twenty-eighth week. After 28 weeks, it is less likely to grow back. Painless bleeding may occur in the middle and late stages of pregnancy, and it is necessary to reduce activities in general, and the specific mode of delivery needs to be judged by a professional doctor. If the lower edge of the placenta is found to be covering the opening of the cervix on ultrasound before the 28th week of pregnancy, you can continue to observe the placenta, which will gradually move upwards as the lower part of the uterus elongates with the prolongation of the pregnancy. After twenty-eight weeks, the lower edge of the placenta still covers the opening of the cervix, which can be diagnosed as placenta praevia, which is relatively dangerous and may lead to painless bleeding. In this case, bed rest is needed in the late pregnancy, and the vaginal bleeding should be closely observed, and any abnormality should be consulted in time. According to the area of the lower edge of the placenta covering the cervical opening, it is classified as low placenta, borderline, partial and complete placenta previa, and the specific mode of delivery should be chosen by a professional doctor according to the specific situation of the pregnant woman. If there are any abnormalities during pregnancy, such as vaginal bleeding and abdominal pain, you need to consult a doctor in a timely manner, and don’t treat the situation on your own, so as not to jeopardize the life of the mother and the child.