Fibroids are benign (noncancerous) growths in the wall of the uterus. The uterus is the reproductive organ where a fetus grows. Fibroids often grow into the uterine cavity. In rare cases, they may protrude from the uterus toward nearby organs. Fibroids may be very small or may grow to eight or more inches in diameter. Usually more than one fibroid is present. About 20%-30% of women of childbearing age, and as many as half of all women, have fibroids. Many do not realize it. Most do not have symptoms until their late 30s or 40s.

Uterine Fibroid
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The cause of fibroids is unknown. Genes and changes in substances that control blood vessel growth may make some women prone to fibroids. Female reproductive hormones stimulate fibroid growth. Fibroids grow larger during pregnancy then shrink after childbirth. Fibroids become less of a problem after menopause. However, symptoms may return with hormone replacement therapy.