Placenta previa is a pregnancy problem in which the placenta blocks the cervix. The placenta is a round, flat organ that forms on the inside wall of the uterus soon after conception. During pregnancy, it gives the baby food and oxygen from the mother.
In a normal pregnancy, the placenta is attached high up in the uterus, away from the cervix. In placenta previa, the placenta forms low in the uterus and covers all or part of the cervix.
If placenta previa is present during labor and delivery, it can cause problems for both mother and baby.
Doctors aren't sure what causes this problem. But some things make you more likely to have it. These are called risk factors.
You can't control most risk factors for placenta previa. For example, you're more likely to have it if you:
Risk factors you can control include:
Some women with placenta previa don't have any symptoms. But others may have warning signs such as:
Call your doctor if you have:
Most cases of placenta previa are found during the second trimester when a woman has a routine ultrasound. Or it may be found when a pregnant woman has vaginal bleeding and gets an ultrasound to find out what is causing it. Some women don't find out that they have placenta previa until they have bleeding at the start of labor.
A pelvic exam will not be done unless you need a C-section right away. A pelvic exam could injure the placenta and cause heavier bleeding.
The kind of treatment you will have depends on:
If your doctor finds out before your 20th week of pregnancy that your placenta is low in your uterus, chances are very good that it will get better on its own. The position of the placenta can change as the uterus grows. So by the end of the pregnancy, the placenta may no longer block the cervix.
If you aren't bleeding, you may not need to be in the hospital. But you will need to be very careful.
If you are bleeding, you may have to stay in the hospital. If you are close to your due date, your baby will be delivered. Doctors always do a C-section when there is a placenta previa at the time of delivery. A vaginal delivery could disturb the placenta and cause severe bleeding.
If your bleeding can be slowed or stopped, your doctor may delay delivery and monitor you and your baby closely. The doctor may do fetal heart monitoring to check your baby's condition.
You may be given:
If your newborn is premature, your baby may be treated in a neonatal intensive care unit, or NICU. Premature babies need to stay in the hospital until they can eat, breathe, and stay warm on their own.
Other Works Consulted
Hull AD, Resnik R (2014). Placenta previa, placenta accreta, abruptio placentae, and vasa previa. In RK Creasy et al., eds., Creasy and Resnik's Maternal-Fetal Medicine, 7th ed., pp. 732–742. Philadelphia: Saunders.
Williams DE, Pridjian G (2011). Obstetrics. In RE Rakel, DP Rakel, eds., Textbook of Family Medicine, 8th ed., pp. 359–401. Philadelphia: Saunders.
Current as of:
February 11, 2020
Author: Healthwise StaffMedical Review: Sarah Marshall MD - Family MedicineKathleen Romito MD - Family MedicineAdam Husney MD - Family MedicineElizabeth T. Russo MD - Internal MedicineRSURemoved
Current as of: February 11, 2020
Author: Healthwise Staff
Medical Review:Sarah Marshall MD - Family Medicine & Kathleen Romito MD - Family Medicine & Adam Husney MD - Family Medicine & Elizabeth T. Russo MD - Internal Medicine & RSURemoved
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