The lower edge of the placenta crossing the inner cervical opening means complete placenta praevia, which is a type of placenta praevia. Placenta praevia is classified as complete placenta praevia, partial placenta praevia, borderline placenta praevia, and low placenta according to the relationship between the edge of the placenta and the cervical opening. Under normal circumstances, the placenta is located on the anterior and posterior walls of the uterus, the lateral walls, and the bottom of the uterus. When the placenta is low, close to or reaching the endocervical opening, especially when it partially or completely covers the endocervical opening, all of them can easily cause painless and unprovoked vaginal bleeding, which is a serious complication during pregnancy. If the condition is serious, it can endanger the life of the pregnant woman and the fetus. If it is placenta praevia, you must pay attention to it during pregnancy, and when vaginal bleeding occurs, go to the hospital in time to avoid delaying the condition.