In general, 48mm from the cervical opening, the placenta can be delivered vaginally, and the progress of labor should be closely monitored. When the ultrasound examination in late pregnancy indicates that the lower edge of the placenta is >20mm from the endocervical opening, the placenta is in a normal position, and after the physician fully evaluates the size of the fetus, pelvic condition and other conditions, it is possible to have a trial of labor through the vagina. Therefore, when the ultrasound indicates that the lower edge of the placenta is 48mm away from the endocervical os, labor can be carried out smoothly, and the progress of labor and changes in fetal heart rate should be closely monitored. During pregnancy, the position of the placenta changes as the weeks of pregnancy increase and the uterus enlarges. In the middle of pregnancy, when the ultrasound indicates that the position of the placenta is close to or has reached the endocervical os, it can be dynamically observed and rechecked in accordance with the doctor’s instructions. With the formation of the lower uterine segment in late pregnancy, the placenta can move up to the normal position. For pregnant women with a history of multiple miscarriages, uterine operations and other high-risk factors, pregnancy management should be strengthened.