What Is Placenta Previa?
Placenta previa is a condition where the placenta stays in the lower part of your uterus throughout your pregnancy. When this happens, the placenta might cover all or part of your cervix — the entrance to the birth canal.
It's normal for the placenta to lie near the cervix in the early part of pregnancy. As your baby grows, it moves higher, until it is further from the cervix by the third trimester.
But sometimes the placenta will stay too low. This increases your risk of severe bleeding during labor when the cervix dilates.
Placenta previa happens in about 1 out of 200 pregnancies.
Types of placenta previa
There are 2 types of placenta previa:
- Partial previa — when the placenta partially blocks the cervix.
- Complete — when the placenta fully covers the cervix.
As you near your due date, your cervix thins and widens so your baby can pass through.
If the placenta is too close to the cervix, blood vessels attached to it can tear. Any type of placenta previa can cause a hemorrhage in your third trimester or when you're in labor.
A low-lying placenta is one that is not blocking the cervix, but is within 2 cm of the cervix opening.
Cause of placenta previa
The exact cause of placenta previa is unknown.
It might be due to scarring or damage to the uterine lining from surgery on the uterus.
Placenta previa risk factors and complications
Some women are more likely to have placenta previa, such as those who:
- Have had a previa in a prior pregnancy.
- Have had a previous C-section.
- Are carrying twins or other multiple pregnancies.
- Are of an advanced age.
- Smoke.
- Have had IVF.
If you've had placenta previa in the past, there's a 4 to 8% chance you could have it again.
Placenta previa can cause life-threatening bleeding during labor.
More than likely, you'll need to have your baby by C-section.
Problems from placenta previa bleeding can include:
- Extra blood loss and the need for a blood transfusion.
- Admission to the ICU.
- The need for a C-section with a hysterectomy (removal of your uterus), if the bleeding does not stop after delivery.
If you have to deliver early, placenta previa might also cause complications for your baby, such as:
- A low birth weight.
- Lower APGAR scores (a rating of your baby's color, heart rate, muscle tone, reflexes, and breathing).
- Risk of respiratory distress syndrome if your baby's lungs haven't fully formed.
While you can't prevent this condition, you and your care team can manage it by optimizing your blood count throughout your pregnancy and being prepared for extra bleeding at delivery.
It's crucial to follow your doctor's advice about ways to reduce the risk of placenta previa bleeding.
Why Choose UPMC Magee-Women's Hospital for Placenta Previa Care?
UPMC's Division of Maternal Fetal Medicine brings a team of experts together to manage high-risk pregnancies, including placenta previa.
We also provide complete care throughout all stages of your pregnancy.