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
normal pregnancy, the placenta is attached high up in the uterus, away from
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
The mother may lose a lot of blood, which can be dangerous for both her and her baby.
The placenta may separate too early from the wall of the uterus. This is called placenta abruptio, and it can cause serious bleeding, too.
The baby may be born too early (premature), at a low birth weight, or with a birth defect.
What causes placenta previa?
Doctors aren't sure what causes this problem. But some things make you more likely to have it. These are called risk
control most risk factors for placenta previa. For example, you're more likely to have it if you:
Have had a surgery that affected your uterus,
such as a D&C or
surgery to remove uterine fibroids (myomectomy).
Any vaginal bleeding in the second or third trimester.
How is placenta previa diagnosed?
Most cases of
placenta previa are found during the second trimester when a woman has a
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.
How is it treated?
The kind of treatment you will
have depends on:
Whether or how much you are bleeding.
How the problem is affecting your health and your baby's
How close you are to your due date.
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.
Avoid all strenuous activity, such as running or lifting.
Don't have sex, and don't put anything in your vagina.
Call your doctor and go to the emergency room right away if you have any vaginal bleeding.
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.
Amniocentesis to find out if your baby's lungs are fully formed.
You may be given:
A blood transfusion if you've lost a lot of blood.
Steroid medicines if you aren't close to your due date. These medicines help get your baby ready for birth by speeding up lung development.
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.
American Congress of Obstetricians and Gynecologists
March of Dimes
1275 Mamaroneck Avenue
White Plains, NY 10605
The March of Dimes tries to improve the health of babies
by preventing birth defects, premature birth, and early death. March of Dimes
supports research, community services, education, and advocacy to save babies'
lives. The organization's website has information on premature birth, birth
defects, birth defects testing, pregnancy, and prenatal care.
How this information was developed to help you make better health decisions.