The placenta is the organ connected to the growing fetus on the wall of the uterus. It receives nutrients to the fetus and removes waste products and facilitates the exchange of oxygen through the mother's blood. The placenta tends to move up and away from the cervix. (opening at the bottom of the uterus) during fetal growth if not The cervix may be blocked. Placenta previa (placenta pre via) occurs when the placenta attaches to the wall of the uterus in the wrong place. near or covering the cervix Placenta previa affects approximately 1 in 200 pregnancies. It is the leading cause of bleeding during pregnancy. It may be total, partial, incremental, or minor. In total placenta previa, the opening is completely closed. in some placenta previa The opening is partially closed. In the marginal placenta previa, the edge of the placenta lies at the edge of the opening. in placenta previa The placenta sticks in the lower part of the uterus, and its edge is near the edge of the opening.