Bleeding during the 9th month of pregnancy can be due to a number of causes ranging from normal changes that occur as your body prepares for labor to potentially life-threatening conditions that require immediate medical attention. It’s important to remember that while bleeding may be directly related to the pregnancy, other conditions not related to the pregnancy may also cause bleeding.
As you approach the end of pregnancy, your cervix -- the lower end of the uterus that allows the baby to pass into the vagina during childbirth -- thins and relaxes in preparation for labor and delivery. As this happens, there is often some discharge called bloody show, which can be thick or thin and is often tinged with a small amount of blood. This is a normal sign of impending labor and can happen up to 2 to 3 weeks before labor begins.
The placenta develops in the uterus during pregnancy and provides nutrition to the fetus through the umbilical cord. In a placental abruption, a portion of the placenta breaks away from the wall of the uterus. This often leads to vaginal bleeding. In some cases, however, a blood clot forms between the placenta and the uterine wall, so that there is no visible bleeding.
Other symptoms of a placental abruption include abdominal pain, back pain, a tender uterus and contractions. Placental abruption can result from abdominal trauma due to a fall or accident, for example. A diagnosis of placental abruption can sometimes be made by ultrasound. This is a potentially serious condition that can deprive the baby of oxygen and nutrients and can cause heavy bleeding in the mother.
Placenta previa refers to a placenta that covers the opening of the cervix. The placenta may cover the entire cervix or just part of it. The authors of a review article published in the April 2013 issue of "Tropical Medicine and International Health" found that the prevalence of placenta previa is low, around 5.0 per 1,000 pregnancies. Risk factors for placenta previa include:
-- older age
-- prior childbirth, cesarean section or abortion
-- smoking or cocaine use during pregnancy
Except for occasional cramping, there are usually no symptoms associated with placenta previa. The diagnosis must be made by ultrasound. Bleeding from a placenta previa is typically bright red, sudden, unexpected and heavy. Placenta previa can be a life-threatening emergency for both the mother and baby.
In rare cases, tearing of the uterine wall -- known as uterine rupture -- can be a cause of vaginal bleeding during late pregnancy. Common symptoms include abdominal pain, heart rate abnormalities in the baby, and signs of low blood volume in the mother. Uterine rupture is most often seen in women who have had previous uterine surgery, such as a cesarean section or removal of uterine fibroids. However, according to a May 2007 review in "Obstetrics and Gynecological Survey," spontaneous rupture can also occur in pregnant women who have had no prior surgery. Uterine rupture is a potentially life-threatening medical emergency. The diagnosis must be made quickly to enable immediate surgical correction.
Bleeding Not Related to Pregnancy
Bleeding late in pregnancy may be due to factors that are unrelated to pregnancy. The vulva, vagina, cervix and rectum are all inspected for the presence of infection, trauma and other abnormalities if bleeding develops. Infections such as genital warts or herpes, certain skin disorders and some precancerous and cancerous skin lesions may lead to bleeding from the external genitals if they become irritated.
Hemorrhoids are common during pregnancy and may bleed easily. Infection, trauma, and noncancerous and cancerous growths on the cervix can also be a source of bleeding. In very rare cases, bleeding may be due to the presence of abnormal connections between veins.
If you experience vaginal bleeding toward the end of your pregnancy, it is important to be evaluated by your doctor right away to determine the source of the bleeding so that appropriate treatment can be given without delay.
Reviewed by: Tina M. St. John, M.D.