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?