The causes of bleeding in the second half of pregnancy are different from those in early pregnancy. Common conditions causing minor bleeding include inflammation of or growths on the cervix . Bleeding can also be serious and pose a threat to the health of the woman or the fetus. It may require treatment in a hospital. The two most common causes are placental abruption and placenta previa.
Preterm labor can also cause vaginal bleeding.
If the placenta becomes detached from the uterine wall before or during labor, vaginal bleeding may occur. Abdominal pain often occurs, too, whether or not there is obvious bleeding. When the placenta becomes detached, the fetus can get less oxygen. This can be dangerous. Women who have already had children, are over 35, have had abruption before, or have sickle cell anemia are at higher risk.