What Is Placenta Previa?

Placenta Previa

Note: The Pregistry website includes expert reports on more than 2000 medications, 300 diseases, and 150 common exposures during pregnancy and lactation. For the topic Placenta Previa, go here. These expert reports are free of charge and can be saved and shared.
Placenta Previa is a potentially serious problem that can seriously complicate your pregnancy. It occurs when the placenta is attached too low within the uterus and either partially or completely blocks the cervix, the exit at the lower end of your uterus.

The placenta is the structure that provides your baby with nutrients and oxygen by connecting him or her to your blood supply. Your baby’s umbilical cord attaches to the placenta. When the placenta is expelled from your uterus right after your baby is born, it is called the afterbirth, and it looks a bit like a deflated red sack.

What Causes Placenta Previa?
There are several possible causes for placenta previa. It can occur with a multiple pregnancy, since there is often more than one placenta and only so much room on the wall of your uterus. It can be due to scarring, such as from a previous cesarean section or a previous pregnancy. It may be due to an abnormally shaped uterus. Older women are at greater risk of having a placenta previa, as are those who have had several babies. Women who smoke or use cocaine also have an increased risk of placenta previa.

What Are the Symptoms?
Because the placenta contains a lot of blood vessels, any problems with the way it is attached to the uterus can cause bleeding. Usually, the first sign of placenta previa is spotting or bleeding during the second half of your pregnancy. The bleeding may be very slight or heavy and may come and go. It is usually bright red. Sometimes the bleeding is accompanied by cramps, but it is often painless.

For some women, they have no symptoms and a placenta previa is found during a routine ultrasound examination.

If you experience any bleeding during your second or third trimester—any at all—call your doctor or midwife immediately. If your bleeding is very severe go to an emergency room as soon as possible. If you are bleeding very heavily, you may go into early labor.

Your doctor or midwife will examine you and make a decision on how serious your condition is. You may be asked to reduce activities or may be placed on complete bed rest. You may even be admitted to the hospital. You will be instructed to avoid sexual intercourse.

Other treatments include giving you medications to help keep your pregnancy going. You may receive shots of steroids to help your baby’s lungs develop faster so that an earlier delivery is safer for him or her. If your pregnancy is after the 36th week, your doctor will discuss delivering your baby early.

If you have a placenta previa, you will almost always need to have a cesarean delivery. Delivering your baby vaginally could cause hemorrhaging and serious loss of blood.

Placenta previa is not very common. It occurs in only about one in 200 births.

Valerie DeBenedette
Valerie DeBenedette is an experienced health and medical writer who lives about an hour north of New York City with a dog that is smaller than her cat. Her work has appeared in magazines, newspapers, newsletters, and on websites. She is a member of the National Association of Science Writers.

Leave a Reply