Third trimester bleeding is when a woman experiences vaginal bleeding during the last part of pregnancy. The third trimester is from week 28 until delivery. Bleeding can occur during the first trimester without cause for alarm, but it can be a sign of serious complications during the third trimester.
The most common cause of third trimester bleeding is referred to as “bloody show.” This is when the mucus plug, a protective barrier at the opening of a pregnant woman’s uterus, exits the woman’s body. When this happens, the woman might notice bloody mucus discharging from her vagina. It is normal for bloody show to appear after 36 weeks of gestation. If a woman experiences additional symptoms or bright red bleeding similar to a period, she should seek medical care.
Cervicitis, or inflammation of the cervix, also can cause some bleeding in the third trimester. Any trauma to the cervix might cause bleeding. Mild spotting after intercourse or a vaginal exam typically is not cause for alarm.
Another possible cause of third trimester bleeding is placental abruption, which is when the placenta detaches from the uterine wall. Placental abruption is fairly rare and usually occurs during the last 12 weeks of pregnancy. Along with vaginal bleeding, a woman might experience stomach pain, contractions, tenderness of the uterus and back pain. Placental abruption might require an emergency cesarean section, and in severe cases, the fetus could die. Risk factors for this condition include smoking, alcohol use, cocaine use, diabetes, high blood pressure, advanced maternal age and history of prior pregnancies.
Bleeding in the third trimester might also be caused by placenta previa, when the placenta is low in the uterus and partly or totally covering the cervix. Most women experience vaginal bleeding without any pain. In some cases, the placenta will move away from the cervix without intervention, but placenta previa often requires emergency care. Most women with this condition require a cesarean section delivery. Risk factors for placenta previa include a history of multiple pregnancies, smoking, advanced maternal age, an abnormal uterus and uterine scarring.
In some cases, third trimester bleeding might indicate pre-term labor. If a woman experiences bloody show before 36 weeks of pregnancy, along with pressure in the lower abdomen, she could be going into early labor. Other signs include a dull ache in the lower back, stomach cramps or contractions.
Bleeding during late pregnancy can indicate very serious medical issues. Some conditions pose a threat to the health and survival of mother and fetus and might require emergency medical care. If a woman experiences third trimester bleeding, she should contact her doctor.