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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
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:
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
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:
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.
Learning about placenta previa:
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.
Other Works Consulted
Hull AD, Resnik R (2009). Placenta previa section of Placenta previa, placenta accreta, abruptio placentae, and vasa previa. In RK Creasy et al., eds., Creasy and Resnik's Maternal Fetal Medicine, 6th ed., pp. 731–734. Philadelphia: Saunders Elsevier.
Williams DE, Pridjian G (2011). Obstetrics. In RE Rakel, DP Rakel, eds., Textbook of Family Medicine, 8th ed., pp. 359–401. Philadelphia: Saunders.
July 17, 2013
Sarah Marshall, MD - Family Medicine & William Gilbert, MD - Maternal and Fetal Medicine
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