It is possible for the placenta to grow up in the later stages. The body of the uterus continues to increase in size during pregnancy, and the isthmus of the uterus softens, gradually extends, lengthens, and thins to become part of the uterine cavity. As the lower part of the uterus extends, the distance between the placenta and the endocervical canal lengthens, and the placenta, which was originally attached to the lower part of the uterus close to or up to the endocervical canal, gradually rises to reach the normal placenta position. The original complete placenta previa can be changed to marginal placenta previa. After 28 weeks of gestation, the placenta previa is found to be less likely to move up to a normal position as the month of gestation deepens, so the ultrasound diagnosis of placenta previa is made when the placenta is in a low position before 28 weeks of gestation. In addition, the lower uterine scar of cesarean section will hinder the upward movement of the placenta position and increase the incidence of placenta praevia. If the placenta is found to be low during pregnancy, it is necessary to consult a doctor for diagnosis and treatment according to the specific situation.