What can cause hemorrhaging during labor?

Hemorrhage (heavy bleeding from the vagina) during labor may be caused by a low-lying placenta, placental abruption, rupture of the uterus, or tearing of the cervix. If the placenta is implanted in the uterus with one edge very close to the cervix, bleeding may occur during labor as the cervix thins and dilates. Bleeding can also be caused by a condition known as placenta previa, in which the placenta completely covers the cervix. Since most women today have at least one sonogram during pregnancy, placenta previa is usually discovered before labor starts, and delivery options and plans can be put in place before labor begins.

Lacerations (tears) of the cervix are not common if labor progresses normally and the baby comes out without assistance. Your provider should check for tears after the birth if bleeding continues and there seems to be no other cause. Lacerations of the vagina, however, are very common. They occur as the baby passes through the vagina, but they rarely cause true hemorrhage unless the birth happens very quickly or instruments (forceps or vacuum cup) are used to help with the birth.

Sometimes the bleeding will stop as the baby descends through the birth canal, and labor can continue. Usually, if the bleeding is heavy during labor, the mother will need a cesarean section.