Third Stage Bleeding
While you are pregnant, your body prepares for the expected blood loss of delivery. On average, women lose about 2 cups of blood during the delivery. The body compensates by producing double its volume of blood. Postpartum hemorrhage is a term that is applied to a mother who loses more than the expected 2 cups of blood or 500 cc during the course of a vaginal birth or over 1,000 cc for a cesarean delivery.
Even though obstetric medicine and technology is very advanced, this type of excessive bleeding still has a major impact on the rate of maternal death.
By the 40th week of pregnancy, 700-1,000 cc of blood flows to the uterus per minute. That means that blood loss can occur very quickly unless there is medical intervention. The uterus is meant to contract after the birth so that the placenta is expelled. After the placenta is expelled, the site of its implantation shrinks and compression of the bleeding vessels stops most of the bleeding.
In some cases, however, the uterus stubbornly fails to contract and the bleeding continues unchecked. This condition is called uterine atony. This can occur when the uterine muscle is tired after a prolonged or very rapid labor. Sometimes uterine atony occurs after labor has been induced with oxytocin. Other causes include uterine clots and incomplete expellation of the placenta in which some pieces remain inside the uterus. Twin births or the birth of a very large baby can distend the uterus and cause uterine atony. In addition to uterine atony, postpartum hemorrhaging can occur when there are lacerations of the cervix or vagina, or in the area of the episiotomy.
Once the birth has taken place, there are signals that separation of the placenta is complete. These signals include a rush of blood and a lengthening of the cord. The body releases oxytocin and prostaglandins, two hormones that cause uterine contractions. The uterine contractions serve to limit blood loss. In most cases, the placenta is expelled after just a few pushes with maybe a gentle tug on the cord by a midwife during a contraction.
If your doctor thinks you may be at risk for postpartum hemorrhage, he will take precautions during your labor and delivery. Such precautions include giving intravenous fluids, administering oxytocin during or just after the delivery, plus external uterine massage and gentle traction on the cord after the birth.