A molar pregnancy is a mass of abnormal tissue (hydatidiform mole) inside the uterus that causes symptoms of pregnancy. A complete molar pregnancy is a tissue mass that can fill the uterus. A partial molar pregnancy may include severely abnormal fetal tissue.

Symptoms of pregnancy are often more intense in a molar pregnancy. Morning sickness may be severe. The uterus may grow at a faster-than-normal rate. And blood pressure may be unusually high.

The cause of molar pregnancy is thought to be a genetic abnormality. The risk of molar pregnancy is higher if you are 15 or younger or 35 or older. If you've had a molar pregnancy in the past, you have a slightly increased risk of having another.

All molar tissue must be removed from the uterus to prevent cancerous cell growth. The tissue is suctioned out through the cervix and vagina (vacuum aspiration). Then the uterus may be scraped of any remaining abnormal cells (curettage). Chemotherapy is used when abnormal tissue is or may become cancerous (trophoblastic cancer).