Read the answers to these commonly asked questions about pregnancy and fibroids:

What is a fibroid tumor?

A fibroid tumor, also known as leiomyoma or myoma, is a mass of compacted muscle and fibrous tissue that grows on the wall (or sometimes on the outside) of the uterus. It can be as small as a pea or as large as a grapefruit. Fibroid tumors occur in 50 to 80 percent of women.

What are the symptoms of fibroids during pregnancy?
  • Heavy vaginal bleeding
  • Abdominal pain
  • Pelvic pressure
  • Frequent urination
  • Constipation

Always report abdominal pain or vaginal bleeding to your doctor immediately.

Will a fibroid tumor complicate my pregnancy?

Fibroids usually develop prior to pregnancy, though many women don't know they have one until they have an ultrasound or the fibroid is discovered during a pelvic exam. If you know prior to pregnancy that you have fibroids, ask your doctor whether their size or position could cause problems, and which symptoms to watch for.

Most women who have one or more of these noncancerous growths experience no pregnancy complications because of them. For the 10 to 30 percent of pregnant women with fibroids who do end up having complications, the most common is abdominal pain, which occasionally may be accompanied by light vaginal bleeding. The baby is rarely affected unless the bleeding is substantial.

Can a fibroid tumor harm the baby?

Probably not. Even if you do experience symptoms, they most likely won't affect the baby. However, your risk of miscarriage and premature delivery does increase slightly if you have fibroids. They occasionally cause the baby to be in an abnormal position for delivery. They can also stall labor, or, if they're located in or near the cervical opening, they may block the baby's passage. All of these (rather rare) problems can increase the likelihood of cesarean delivery.

How will a doctor treat fibroid tumors during pregnancy?

Painful fibroids are usually treated with bed rest, ice packs, and — when necessary — medication. Your doctor will recommend the treatment that's safest for you. Symptoms usually subside within a few days.

Fibroids sometimes grow larger during pregnancy, due in part to pregnancy hormones. For reasons that are not well understood, a fibroid may also get smaller during pregnancy. Your doctor may recommend ultrasound examinations to see whether your fibroid is growing or likely to cause complications.