Some complications of pregnancy also cause problems during labor or delivery. For example, preeclampsia (see Complications of Pregnancy: Preeclampsia), which involves high blood pressure accompanied by protein in the urine, can develop any time from the 20th week of pregnancy through the 6 weeks after delivery. Preeclampsia may lead to premature detachment of the placenta from the uterus (placental abruption—see Complications of Pregnancy: Placental Abruption (Abruptio Placentae)) and problems in the newborn.

Other complications develop only after labor and delivery occur.

Amniotic Fluid Embolism

Very rarely, a volume of amniotic fluid—the fluid that surrounds the fetus in the uterus—enters the woman's bloodstream, usually during a particularly difficult labor. The fluid can cause a serious reaction that involves a rapid heart rate, irregular heart rhythm, collapse, shock, or even cardiac arrest and death (in about one fifth of women). Widespread blood clotting (disseminated intravascular coagulation), sometimes also with bleeding, is a common complication, requiring emergency care (see Bleeding and Clotting Disorders: Disseminated Intravascular Coagulation (DIC)).

Prompt diagnosis and treatment are essential. Women may be given a blood transfusion. They may require assistance with breathing or drugs to help the heart contract.

Excessive Uterine Bleeding

Excessive bleeding from the uterus (postpartum hemorrhage) refers to loss of more than about 1 pint of blood immediately after vaginal delivery of a baby or loss of more than about 2 pints after cesarean delivery.

After the baby is delivered, excessive bleeding from the uterus is a major concern. Ordinarily, the woman loses about 1 pint of blood after delivery. Blood is lost because some blood vessels are opened when the placenta detaches from the uterus. The contractions of the uterus help close these vessels until the vessels can heal.

Loss of more than about 1 pint of blood during or after the third stage of labor (when the placenta is delivered) is considered excessive. Severe blood loss usually occurs soon after delivery but may occur as late as 1 month afterward.

Excessive bleeding may result when the contractions of the uterus after delivery are impaired. Then, the blood vessels that were opened when the placenta detached continue to bleed. Contractions may be impaired in the following situations:

• When the uterus has been stretched too much—for example, by too much amniotic fluid in the uterus, by several fetuses, or by a very large fetus
• When a piece of placenta remains inside the uterus after delivery
• When labor was prolonged or abnormal
• When a woman has delivered more than five babies
• When a muscle-relaxing anesthetic was used during labor and delivery

Excessive bleeding can also result when the following occurs:

• When the vagina or cervix is torn or cut during delivery
• When the blood level of fibrinogen (which helps blood to clot) is low
• When a woman has a bleeding disorder that interferes with clotting
• Rarely, when the uterus ruptures or is turned inside out (inverted)

Excessive bleeding after one delivery may increase the risk of excessive bleeding after subsequent deliveries. Fibroids in the uterus may also increase the risk.

Prevention

Before a woman goes into labor, doctors take steps to prevent or to prepare for excessive bleeding after delivery. For example, they determine whether the woman has any conditions that increase the risk of bleeding (such as too much amniotic fluid). If the woman has an unusual blood type, doctors make sure that her blood type is available. Delivery should be slow and as gentle as possible. After delivery of the placenta, the woman is monitored for at least 1 hour to make sure that the uterus has contracted and to assess bleeding.

Treatment

If severe bleeding occurs, the woman's lower abdomen is massaged, and she is given oxytocin continuously through an intravenous line. These measures help the uterus contract. If bleeding continues, drugs that help the uterus contract can be injected into a muscle, placed as a tablet in the rectum, or, during cesarean delivery, injected into the uterus. The woman may need a blood transfusion.

Doctors look for the cause of excessive bleeding. The uterus may be examined to see whether any fragments of the placenta remain. Dilation and curettage may be done to remove these fragments. In this procedure, a small, sharp instrument (curet) is passed through the cervix (which is usually still open from the delivery—see Diagnosis of Gynecologic Disorders: Dilation and Curettage). The curet is used to remove the retained fragments. This procedure requires an anesthetic. The cervix and vagina are examined for tears.

If the uterus cannot be stimulated to contract and bleeding continues, the arteries supplying blood to the uterus may have to be compressed to stop blood flow. For example, a balloon may be inserted into the uterus and inflated, packing may be inserted into the uterus, or a doctor may place stitches (sutures) around the bottom of the uterus. The procedures used usually do not cause infertility, abnormalities in menstruation, or other lasting problems. Removal of the uterus (hysterectomy) is rarely necessary to stop the bleeding.

Inverted Uterus

Very rarely, the uterus is turned inside out (inverted), so that it protrudes through the cervix and into or through the vagina. The uterus may be inverted if the placenta is firmly attached and doctors pull hard to remove it.

An inverted uterus is a medical emergency that must be treated promptly. Doctors return the uterus to its normal position (reinvert it) by hand. Pain relievers, sedatives, and sometimes a general anesthetic may be needed. Most women recover fully after this procedure. Occasionally, surgery is required to return the uterus to its normal position.

Placenta Accreta

Placenta accreta is a placenta with an abnormally firm attachment to the uterus.

When the placenta is too firmly attached, parts of the placenta may remain in the uterus after delivery. In these cases, delivery is delayed, and the risks of bleeding and infection in the uterus are increased. Bleeding may be life threatening.

This complication is more likely to occur in women

• Who have had a cesarean delivery
• Whose placenta covers the cervix
• Who are over 35
• Who have been pregnant several times
• Who have had fibroids surgically removed
• Who have disorders of the lining of the uterus (endometrium) such as Asherman's syndrome

Having a cesarean delivery greatly increases the risk of this complication. The more cesarean deliveries a woman has had, the higher the risk.

Diagnosis and Treatment

Before delivery, doctors can sometimes diagnose placenta accreta when ultrasonography or magnetic resonance imaging (MRI) is done. During delivery, the disorder is suspected if the placenta has not been delivered within 30 minutes after the baby's delivery, if doctors cannot separate the placenta from the uterus by hand, or if attempting to remove the placenta results in profuse bleeding.

Hysterectomy is the safest procedure. However, if future childbearing is important to the woman and if bleeding is not profuse, the abnormal area can sometimes be repaired.

Uterine Rupture

Uterine rupture is a spontaneous tearing open of the uterus that may result in the fetus floating in the abdomen.

Rupture of the uterus is very rare. It is an emergency requiring immediate treatment.

The uterus can rupture before or during labor. Rupture is more likely in women who have had a cesarean delivery or who have had surgery on the uterus. The risk of uterine rupture for women who have had a cesarean delivery increases if they require induction of labor instead of having spontaneous labor. Rupture causes severe, constant pain in the abdomen and an abnormally slow heart rate in the fetus. The fetus must be delivered immediately. The uterus is repaired surgically.

Last full review/revision December 2008 by Julie S. Moldenhauer, MD