The main symptom of low placenta is unprovoked, painless recurrent vaginal bleeding in late pregnancy. Before the 28th week of pregnancy, if the placenta is attached to the lower part of the uterus and the edge is less than 2cm from the endocervical opening, it is considered placenta hypoplasia. At this time, there are usually few special symptoms. After 28 weeks of pregnancy, if the placenta is in a low position and the edge reaches the endocervical os or covers the endocervical os, it is considered placenta praevia. Recurrent vaginal bleeding without cause and without pain may occur. Depending on the position of the placenta from the endocervical opening, it can be categorized as complete, borderline, or partial placenta previa. Complete placenta previa first bleeds earlier and marginal placenta previa first bleeds later. During pregnancy, it is important to pay attention to the labor and delivery tests. If placenta praevia is present, pregnant women should minimize their activities and focus on resting to reduce the risk of bleeding, and should seek medical attention as soon as there is vaginal bleeding.