The placenta is an appendage of the fetus. During pregnancy, it mainly provides blood supply for the growth and development of the fetus. When examining the placenta during pregnancy, attention should be paid to the relationship between the lower edge of the placenta and the internal os of the cervix, the thickness of the placenta, the maturity of the placenta, and the location where the placenta attaches. The placenta can attach to any part within the uterine cavity. It can attach to the anterior wall of the uterus, the posterior wall of the uterus, or the fundus of the uterus. If the placenta attaches to the anterior wall of the uterus, it is called an anterior placenta. If the placenta attaches to the posterior wall of the uterus, it is called a posterior placenta. Both anterior and posterior placentas are normal types of placenta, and there is not much difference between them. The main difference refers to whether the placenta attaches to the anterior or posterior wall. Some pregnant women think that the posterior placenta is better than the anterior one, or vice versa. These ideas are wrong. In clinical practice, there is no difference between anterior and posterior placentas. However, attention should be paid to the relationship between the lower edge of the placenta and the internal os of the cervix to rule out placenta previa.