The lower edge of the placenta in the third trimester of pregnancy covers the inner mouth of the cervix, which is a state of placenta hypoplasia. The lower edge of the placenta in the third trimester of pregnancy covers the opening of the uterine cervix, which is considered to be a state of placenta hypoplasia. At this time, the placenta itself occupies half of the area of the uterine wall, and the chances for the placenta to be close to or to cover the opening of the uterine cervix are more likely to occur. In the third trimester of pregnancy, with the increase of gestational weeks and the gradual development of the fetus, the position of the placenta may slowly move upward, and the placenta is not considered to be placenta praevia if it grows to a normal position before the 28th week of pregnancy. If there is no change in the position of the placenta after the 28th week of pregnancy, the placenta praevia is considered to be placenta praevia, and there may be painless vaginal bleeding during pregnancy, which will increase the chance of preterm delivery of the fetus. It is important to have regular and proper pregnancy checkups to be able to detect any abnormalities in the development of the fetus.