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
About 1 out of 1,500 women with early pregnancy
symptoms has a molar pregnancy.1 This means that 1,499
women out of 1,500 don't have this problem.
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. The sperm grows on its own, but
it can only become a lump of tissue. It cannot become a fetus. As this tissue
grows, it looks a bit like a cluster of grapes. This cluster of tissue 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
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 35.2
- A history of molar pregnancy, especially if you've had two or more.3
- 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
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:
- Bleeding from the vagina.
uterus that is larger than normal.
- Severe nausea and vomiting.
- Signs of
hyperthyroidism. These include feeling nervous or
tired, having a fast or irregular heartbeat, and sweating a lot.
- An uncomfortable feeling in the pelvis.
discharge of tissue that is shaped like grapes. This is usually a sign of molar
Most of these symptoms can also occur with a normal
pregnancy, a multiple pregnancy, or a miscarriage.
How is a molar pregnancy diagnosed?
can confirm a molar pregnancy with:
Your doctor can also find a molar pregnancy during a
ultrasound in early pregnancy. Partial molar
pregnancies are often found when a woman is treated for an
What are the risks of having a molar pregnancy?