Delivery Options With Low-Lying Placenta

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Delivery Options With Low-Lying Placenta

Question:

I'm 30 weeks pregnant and have a "low-lying placenta." It continues to move away from my cervix. Is a Caesarean section necessary when dealing with a low-lying placenta? What are my chances of being able to have a vaginal delivery?

Answer:

The cervix is the portion of the uterus that dilates during labor. It opens to the vagina and allows the baby to pass through the birth canal during delivery.

The placenta is the organ that supplies the baby with oxygen and nutrients. It receives a great deal of blood from the mother and baby. Therefore, any placental tissue that covers the cervix is at risk for bleeding before or during labor. Because this bleeding can be quite heavy, doctors recommend Caesarean delivery.

A placenta that covers all or part of the cervix is called a placenta previa.

Early in pregnancy, it can be difficult to tell where the placenta ends and the cervix begins. Later in pregnancy, this becomes clearer.

In the second or early third trimester, if the placenta appears close to the cervix but is not clearly covering it, it may be called a "low-lying placenta." As the pregnancy progresses, it will become clearer if this low-lying placenta is really a placenta previa (meaning a Caesarean delivery will be recommended) or if it is far enough from the cervix to permit vaginal delivery.

People sometimes speak of low-lying placentas as "moving," but the placenta never really moves. Tissue at the edge may shrink and disappear, giving the illusion of movement. Or a clearer view may reveal that it was never really covering the cervix.

Most placentas (90%) that are deemed low lying in early pregnancy will not be placenta previas late in pregnancy. Most women who are told they have a low-lying placenta on a second trimester ultrasound can have a vaginal delivery.

Jeffrey Ecker, M.D. is an Associate Professor of obstetrics, gynecology and reproductive biology at Harvard Medical School and a member of the Department of Obstetrics and Gynecology at Massachusetts General Hospital, where he practices maternal-fetal medicine.

Last updated:	July 20, 2009