Molar Pregnancy - Topic Overview
What is a molar pregnancy?
A molar pregnancy happens when tissue that normally becomes a fetus instead becomes an abnormal growth in your uterus. Even though it isn't an embryo, this growth triggers symptoms of pregnancy.
A molar pregnancy should be treated right away. This will make sure that all of the tissue is removed. This tissue can cause serious problems in some women.
About 1 out of 1,500 women with early pregnancy symptoms has a molar pregnancy.
What causes a molar pregnancy?
Molar pregnancy is thought to be caused by a problem with the genetic information of an egg or sperm. There are two types of molar pregnancy: complete and partial.
Complete molar pregnancy. An egg with no genetic information is fertilized by a sperm. It does not develop into a fetus but continues to grow as a lump of abnormal tissue that looks a bit like a cluster of grapes and can fill the uterus.
Partial molar pregnancy. An egg is fertilized by two sperm. The placenta becomes the molar growth. Any fetal tissue that forms is likely to have severe defects.
Sometimes a pregnancy that seems to be twins is found to be one fetus and one molar pregnancy. But this is very rare.
Things that may increase your risk of having a molar pregnancy include:
Age. The risk for complete molar pregnancy steadily increases after age 35.
A history of molar pregnancy, especially if you've had two or more.
A history of miscarriage.
A diet low in carotene. Carotene is a form of vitamin A. Women who don't get enough of this vitamin have a higher rate of complete molar pregnancy.
What are the symptoms?
A molar pregnancy causes the same early symptoms that a normal pregnancy does, such as a missed period or morning sickness. But a molar pregnancy usually causes other symptoms too. These may include:
Most of these symptoms can also occur with a normal pregnancy, a multiple pregnancy, or a miscarriage.