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Placenta previa

Placenta previa is when the placenta covers the cervix during pregnancy. It can cause bleeding and requires monitoring.

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Placenta previa

Placenta previa is when the placenta covers the cervix during pregnancy. It can cause bleeding and requires monitoring.

    Key points about placenta previa

    • Placenta previa is a cause of bleeding late in pregnancy. This is after about 20 weeks.
    • It causes bleeding because the placenta is close to or covers the cervix.
    • Bleeding with placenta previa is painless.
    • You may need bed rest or early delivery of your baby.

    What is placenta previa?

    Bleeding can happen at any time during pregnancy. Placenta previa can cause bleeding late in pregnancy. This means after about 20 weeks.

    When the placenta is attached close to the opening of the uterus (cervix) or covers the cervix, it is called placenta previa. There are 3 types of placenta previa:

    • Complete placenta previa. The placenta completely covers the cervix.
    • Partial placenta previa. The placenta is partly over the cervix.
    • Marginal placenta previa. The placenta is near the edge of the cervix.

    What are the symptoms of placenta previa?

    The most common symptom of placenta previa is bright red, painless bleeding from the vagina. This is most common in the third trimester of pregnancy.

    The symptoms of placenta previa may look like other health conditions. Make sure to see your healthcare provider for a diagnosis.

    When should I contact my doctor?

    Seek care immediately if:

    • You have severe vaginal bleeding or substantial spotting — a hemorrhage can be life-threatening.
    • You experience pain with vaginal bleeding.

    Call your doctor if:

    • You have mild vaginal bleeding in the second or third trimester.
    • You want to be referred to a specialist.

    How to make an appointment

    If you suspect you have placenta previa or have already received a diagnosis from your obstetrician-gynecologist, schedule an appointment with a maternal-fetal medicine physician. They will help monitor your condition and consult with UW Medicine's full team of obstetrics experts to help determine the best course of care.

    Placenta previa care at UW Medicine

    If you're diagnosed with placenta previa, we'll care for you with close monitoring throughout your pregnancy. Our specialists use ultrasound technology to diagnose and provide frequent monitoring for all cases of placenta previa.

    UW Medicine also provides additional resources, such as equipment and access to a blood bank, to help reach the best possible outcome for you and your baby. We care for other placenta-related pregnancy complications that may be life-threatening.

    You and your baby will have access to highly trained medical staff and healthcare experts who have expertise in critical care. Our resources include obstetricians, maternal-fetal medicine specialists, a NICU unit to care for preterm babies, medical and surgical ICUs, anesthesia teams and hematologists.

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    What causes placenta previa?

    Researchers don't know what causes placenta previa. It is more likely to happen with certain conditions. These include:

    • Past pregnancies
    • Tumors (fibroids) in the uterus. These are not cancer.
    • Past uterine surgeries or cesarean deliveries
    • Woman who is older than 35
    • Woman who is African American or of another nonwhite ethnic background
    • Cigarette smoking
    • Being pregnant with a boy

    How is placenta previa diagnosed?

    Your healthcare provider will ask about your health history. he or he will do a physical exam. The provider will also do an ultrasound. An ultrasound uses sound waves to make a picture of the organs. It can show where the placenta is and how much is covering the cervix. You may have a transvaginal ultrasound instead.

    An ultrasound may show that a placenta is near the cervix in early pregnancy. But only a few women will develop true placenta previa. It is common for the edge of the placenta to move away from the cervix as the uterus grows.

    How is placenta previa treated?

    There is no treatment to change the position of the placenta. You may need:

    • More ultrasounds to track where the placenta is
    • Bed rest or hospital stay
    • Early delivery of the baby. This will be based on how much bleeding you have, how far along your baby is, and how healthy the baby is.
    • Cesarean section delivery
    • Blood transfusion for severe blood loss

    What are possible complications of placenta previa?

    The greatest risk of placenta previa is too much bleeding (hemorrhage). Bleeding often happens as the lower part of the uterus thins during the third trimester of pregnancy. This causes the area of the placenta over the cervix to bleed. The risk of bleeding is higher if a lot of the placenta covers the cervix. Other complications include:

    • Placenta doesn't attach to the uterus as it should
    • Slowed growth of your baby in the uterus
    • Preterm birth (before 37 weeks of pregnancy)
    • Birth defects