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What is an Anterior Placenta?

H. Colledge
H. Colledge

An anterior placenta is one which is attached to the front wall of the uterus, or womb, rather than the more usual position on the back wall nearest the spine. When the placenta is at the front of the uterus in this way it does not represent a health risk, although it could be inconvenient in minor ways. Since the baby is positioned behind the placenta, it might be harder for the mother to feel the baby moving because the placenta is in the way, and it could be more difficult for medical staff to listen to heart sounds or perform amniocentesis or, in some cases, a cesarean section. In the majority of cases an anterior placenta does not cause any problems, and many will move to a posterior position later in the pregnancy.

The placenta is the organ which develops inside the uterus during pregnancy and which enables substances to pass between the blood supply of the mother and that of the baby, while still keeping the two circulations separate. Through the placenta, important oxygen and nutrients are obtained from the mother's blood supply to meet the needs of the growing fetus. In addition to the possibility of having an anterior placenta, the posterior, top, and right or left sides of the uterus can all be normal places for placenta development.

A woman with an anterior placenta may find it harder to feel her baby moving because the placenta is in the way.
A woman with an anterior placenta may find it harder to feel her baby moving because the placenta is in the way.

Where the placenta initially develops depends on where in the uterus the fertilized egg becomes implanted after it emerges from the Fallopian tube. Extremely rarely, an anterior placenta may attach itself to the site of an old cesarean scar, causing a condition known as placenta accreta. In placenta accreta the placenta's attachment to the uterus is stronger than normal, and very occasionally it may even grow into or beyond the uterus wall. As the condition involves the possibility of severe hemorrhage, the birth is managed very carefully, with access to blood transfusions and a surgical team ready to perform a hysterectomy if required.

Normally, the placenta attaches to the back wall of the uterus.
Normally, the placenta attaches to the back wall of the uterus.

While an anterior placenta is usually unlikely to cause a problem, if the placenta moves lower down in the uterus so that it comes between the baby and the entrance to the womb, or cervix, this is known as placenta previa. Placenta previa is a situation which carries an increased risk of hemorrhage occurring. Sometimes, cases of placenta previa which are detected in the earlier stages of a pregnancy, using ultrasound, will later resolve as the placenta moves higher up. If not, babies may be delivered early, possibly by cesarean section.

Discussion Comments

anon992401

I am 16 weeks and was told at 15 weeks that I have an anterior placenta. I was feeling baby movements at 12-13 weeks and then they stopped so my placenta must be moving around my uterus. This really scares me thinking that it could move into placenta previa covering my cervix. Who would have ever thought a placenta could migrate!!

anon294749

I have a anterior placenta also, and I hope that it doesn't turn into placenta previa because I don't want to have a c-section. This is my first child and I want to have her naturally.

ElizaBennett

I had trouble feeling my baby move and my midwife said that an anterior placenta could muffle baby's movements and that might be the problem. (I didn't have any early ultrasounds.) Well, anterior placenta turned into complete placenta previa by the end of my second trimester!

To clarify the end of the article, a c-section is almost always necessary for placenta previa. I was planning a natural birth and I'm as crunchy as they come, but even I had to agree that a c-section was the way to go. A couple hundred years ago, my baby and I wold probably have died.

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    • A woman with an anterior placenta may find it harder to feel her baby moving because the placenta is in the way.
      By: auremar
      A woman with an anterior placenta may find it harder to feel her baby moving because the placenta is in the way.
    • Normally, the placenta attaches to the back wall of the uterus.
      By: Alila Medical Media
      Normally, the placenta attaches to the back wall of the uterus.
    • An anterior placenta becomes attached to the front wall of the uterus, instead of the back wall which is the more usual position.
      By: Patricia Hofmeester
      An anterior placenta becomes attached to the front wall of the uterus, instead of the back wall which is the more usual position.
    • Vaginal ultrasound probes may be inserted into the vagina to obtain an image of the uterus.
      By: zayacsk
      Vaginal ultrasound probes may be inserted into the vagina to obtain an image of the uterus.
    • The placenta develops inside of the uterus during pregnancy.
      By: ProMotion
      The placenta develops inside of the uterus during pregnancy.