The fetus has a certain degree of mobility in the uterus, so in principle it cannot be in the anterior or posterior wall. Regarding the fetus located in the anterior and posterior wall, it should refer to the placenta, once pregnancy, the position of the placenta is relatively fixed, the placenta anterior or posterior wall is the normal position of the placenta attached to the normal position, there will be no effect on the pregnancy, the fetus. However, if the placenta is attached to the lower part of the uterus, or even the cervix, it is called placenta praevia instead of placenta anterior, which will affect labor. At the same time, because the muscles of the lower part of the uterus are relatively weak and there are relatively few blood vessels, the placenta attached in this position often can not get sufficient nutrition, and implantation of the placenta may occur, which may cause more serious harm to the delivery of the baby.