Placental abruption is most likely to occur in the last trimester of pregnancy, especially in the last few weeks before birth. Classic signs and symptoms of placental abruption include:
- Vaginal bleeding
- Abdominal pain
- Back pain
- Uterine tenderness
- Rapid uterine contractions, often coming one right after another
Abdominal pain and back pain often begin suddenly. The amount of vaginal bleeding can vary greatly, and doesn't necessarily correspond to how much of the placenta has separated from the inner wall of the uterus. It's even possible to have a severe placental abruption and no visible bleeding, if the blood becomes trapped inside the uterus by the placenta.
In some cases, placental abruption develops slowly. If this happens, you might notice light, intermittent vaginal bleeding. Your baby might not grow as quickly as expected, and you might have low amniotic fluid (oligohydramnios) or other complications.
When to see a doctor
Seek emergency care if you experience any classic signs or symptoms of placental abruption, including:
- Vaginal bleeding
- Abdominal pain
- Severe back pain
- Rapid uterine contractions
The specific cause of placental abruption is often unknown. Possible causes include trauma or injury to the abdomen — from an auto accident or fall, for example — or rapid loss of the fluid that surrounds and cushions the baby in the uterus (amniotic fluid).
Various factors can increase the risk of placental abruption, including:
- Previous placental abruption. If you've experienced placental abruption before, you're at higher risk of experiencing it again.
- High blood pressure. High blood pressure — whether chronic or as a result of pregnancy — increases the risk of placental abruption.
- Abdominal trauma. Trauma to your abdomen — such as from a fall or other type of blow to the abdomen — makes placental abruption more likely.
- Substance abuse. Placental abruption is more common in women who smoke or use cocaine during pregnancy.
- Premature rupture of the membranes. During pregnancy, the baby is surrounded and cushioned by a fluid-filled membrane called the amniotic sac. The risk of placental abruption increases if the sac leaks or breaks before labor begins.
- Blood-clotting disorders. Any condition that impairs your blood's ability to clot increases the risk of placental abruption.
- Multiple pregnancy. If you're carrying more than one baby, the delivery of the first baby can cause changes in the uterus that trigger placental abruption before the other baby or babies are delivered.
- Maternal age. Placental abruption is more common in older women, especially after age 40.
Placental abruption can cause life-threatening problems for both mother and baby.
For the mother, placental abruption can lead to:
- Shock due to blood loss
- Blood clotting problems (disseminated intravascular coagulation)
- The need for a blood transfusion
- Failure of the kidneys or other organs
For the baby, placental abruption can lead to:
- Deprivation of oxygen and nutrients
- Premature birth
After the baby is born, bleeding from the site of the placental attachment is likely. If the bleeding can't be controlled, emergency removal of the uterus (hysterectomy) might be needed.
You can't directly prevent placental abruption, but you can decrease certain risk factors that make placental abruption more likely. For example, don't smoke or use illegal drugs, such as cocaine. If you have high blood pressure, work with your health care provider to control the condition.
If you've had any kind of abdominal trauma — from an auto accident, fall or other injury — seek immediate medical help because of the increased risk of placental abruption and other complications.
If you've had a placental abruption and are planning another pregnancy, talk to your health care provider to see if there are any ways you might be able to reduce the risk of another abruption before conceiving again. Expect your health care provider to carefully monitor your condition throughout the pregnancy.