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The placenta is an organ that provides oxygen and nutrition to a baby in the womb. It also removes wastes from the baby. Placenta previa is when this organ covers part or all of the cervix that the baby must pass through to be born.
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The cause is not known. It may be due to problems with how the placenta implants due to injury to the lining of the uterus and scarring from:
Things that may raise the risk of this problem are:
- Prior cesarean delivery
- Prior abortion
- Being pregnant with a male fetus
- Smoking or cocaine use in the mother
Symptoms differ from person to person. It depends on how much of the cervix is covered. The main sign is painless bleeding from the birth canal. It can range from light to heavy. It most often happens after 20 weeks of pregnancy, usually after sex.
The doctor will ask about symptoms and health history. An ultrasound will be done. This can confirm the diagnosis.
The goal of treatment is to manage the bleeding and give the baby time to grow. How this is done will depend on the amount of bleeding a person has and how many weeks of pregnancy have passed. Options are:
A C-section will be needed to deliver the baby if the placenta covers the cervix, there is heavy bleeding during labor, or other health problems happen.
The American Congress of Obstetricians and Gynecologists
Family Doctor—American Academy of Family Physicians
Women's Health Matters
Placenta previa. American Pregnancy Association website. Available at: https://americanpregnancy.org/healthy-pregnancy/pregnancy-complications/placenta-previa. Accessed May 9, 2022.
Placenta previa. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/placenta-previa. Accessed May 9, 2022.
Pregnancy complications. Office on Women's Health website. Available at: https://www.womenshealth.gov/pregnancy/youre-pregnant-now-what/pregnancy-complications. Accessed May 9, 2022.
- Reviewer: EBSCO Medical Review Board Beverly Siegal, MD, FACOG
- Update Date: 05/09/2022