Skip to content
My WebMD Sign In, Sign Up

Health & Pregnancy

Font Size

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.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 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 35.2
  • 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 pregnancy.2

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.
  • A 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.
  • Vaginal discharge of tissue that is shaped like grapes. This is usually a sign of molar pregnancy.

Most of these symptoms can also occur with a normal pregnancy, a multiple pregnancy, or a miscarriage.

How is a molar pregnancy diagnosed?

Your doctor can confirm a molar pregnancy with:

Your doctor can also find a molar pregnancy during a routine ultrasound in early pregnancy. Partial molar pregnancies are often found when a woman is treated for an incomplete miscarriage.

1|2

WebMD Medical Reference from Healthwise

Last Updated: October 11, 2011
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
Next Article:

Pregnancy Week-By-Week Newsletter

Delivered right to your inbox, get pictures and facts on
what to expect each week of your pregnancy.

Today on WebMD

Woman smiling as she reads pregnancy test
Slideshow
pregnant woman with salad
Quiz
 
pregnancy am i pregnant
Article
calendar and baby buggy
Tool
 

slideshow fetal development
Slideshow
pregnancy first trimester warning signs
Article
 
What Causes Bipolar
Video
Woman trying on dress in store
Slideshow
 

pregnant woman
Article
Close up on eyes of baby breastfeeding
Video
 
healthtool pregnancy calendar
Tool
eddleman prepare your body pregnancy
Video