Pregnancy Complications: Common Causes of Hemorrhage

Common causes of hemorrhage during labor and delivery include:

• atony of the uterus (failure of the uterus to contract after delivery);
• tears in the vagina or cervix;
• fragments of the placenta remaining in the uterus;
• placenta previa (when the placenta implants too close to the cervix);
• placenta accreta (when the placenta implants too deep in the wall of the uterus);
• rupture of the uterus; and
• Inherited abnormalities in blood clotting.

The average blood loss during a normal vaginal delivery is approximately 500 cubic centimeters (half of a liter), compared to approximately 1,000 cubic centimeters (one liter) during a cesarean section. Of note, the circulating blood volume of a pregnant woman is nearly 50% greater than in the non-pregnant state. Approximately 4% of vaginal deliveries result in postpartum hemorrhage (excessive blood loss after delivery); between 6 to 7% of cesarean sections result in postpartum hemorrhage.