Uterine fibroids are tumors or growths, made up of muscle cells and other tissues that grow within the wall of the uterus (or womb). Although fibroids are sometimes called tumors, they are almost always benign (not cancerous). Fibroids can grow as a single growth or in clusters (or groups). Their size can vary from small, like an apple seed (or less than one inch), to even larger than a grapefruit, or eight inches across or more. No one knows for sure what causes fibroids. Researchers have some theories, but most likely, fibroids are the result of many factors interacting with each other. These factors could be hormonal (affected by estrogen levels), genetic (running in families), environmental, or a combination of all three. Because no one knows for sure what causes fibroids, we also don't know what causes them to grow or shrink. For the most part, fibroids stop growing or shrink after menopause. But, this is not true for all women with fibroids.

Most of the time, fibroids grow in women of childbearing age. While no one knows for sure what will increase a woman's chances of getting fibroids, researchers have found that African American women are 2 to 3 times more likely to get them than women of other racial groups. African American women also tend to get fibroids at a younger age than do other women with fibroids.

Publications

1. Fibroid Embolization (Copyright © UCLA Medical Group) - An on-line publication which describes the fibroid emoblization procedure. This procedure blocks the blood supply that feeds the fibroids which causes the fibroids to shrink. This procedure in less invasive than a hysterectomy.

2. Frequently Asked Questions - Uterine Fibroids - This fact sheet contains information on fibroids, the causes, who is at risk, symptoms, and treatment options.

3. Uterine Fibroids - This brochure describes the symptoms and treatment of uterine leiomyomata (fibroid tumors). It also explains what is known about the causes of uterine fibroids, their impact on a woman's fertility, fibroids' relation to cancer, the medical research on uterine fibroids, and lists resources to contact for more information.

Organizations

1. Division of Vascular Interventional Radiology, Georgetown University Medical Center

2. National Institute of Child Health and Human Development, NIH, HHS

3. National Uterine Fibroid Foundation