What Is Placenta Previa, and What Are the Symptoms?

The placenta is an organ that grows inside the lining of your uterus during pregnancy. It connects to the umbilical cord and carries oxygen and nutrients from you to your unborn child. It also moves waste away from your baby.

Placenta previa happens when the placenta partly or completely covers the cervix, which is the opening of the uterus. Your baby passes from the uterus into the cervix and through the birth canal during a vaginal delivery. Normally, the placenta attaches toward the top of the uterus, away from the cervix.

Here’s what happens with placenta previa: As your cervix opens during labor, it can cause blood vessels that connect the placenta to the uterus to tear. This can lead to bleeding and put both you and your baby at risk. Nearly all women who have this condition will have to have a C-section to keep this from happening.

Who’s at Risk?

Placenta previa occurs in about 1 out of every 200 pregnancies. You may be more likely to develop it if you:

  • Smoke cigarettes or use cocaine
  • Are 35 or older
  • Have been pregnant before
  • Have had a C-section before
  • Have had other types of surgery on your uterus
  • Are pregnant with more than one baby

What Are the Symptoms?

It’s possible you won’t know you have placenta previa until your doctor finds it during a routine ultrasound.

The most common sign is bright red bleeding from the vagina during the second half of your pregnancy. It can range from light to heavy, and it’s often painless. But some women also have contractions with the bleeding.

When to Contact Your Doctor

Make an appointment if you have bleeding during your second or third trimester. If it’s severe, go to the hospital.

WebMD Medical Reference Reviewed by Kecia Gaither, MD, MPH on October 26, 2016

Sources

SOURCES:

NHS Choices: “What Is the Placenta?”

March of Dimes: “Placenta Previa.”

Mayo Clinic: “Placenta Previa.”

© 2016 WebMD, LLC. All rights reserved.

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