We mentioned earlier, that, during your pregnancy, your uterus stretches and expands, along with the growing baby. As it expands, more blood vessels also grow inside the uterus to nourish it.
If the blood vessels in the uterus are ruptured for any reason, it may result in serious loss of blood. Uterine contractions that usually occur after the baby is delivered help prevent serious bleeding from blood vessels in the wall of the uterus, and also where the placenta was previously attached. The contractions squeeze shut any open blood vessels.
One of the most common causes of postpartum hemorrhage is called uterine atony. This means that the uterus does not contract during and after the placenta is delivered.
In some cases, the doctor may try to stimulate uterine contractions by massaging the uterus. Other possible treatments include medication to cause the uterus to contract after the baby is delivered. In rare cases, additional surgery may be required to stop the bleeding.