Fibroids are masses of muscular tissue that can develop within the wall of the uterus. They are the most common noncancerous tumor in premenopausal women. You may hear your health care professional call fibroids by other terms, including uterine leiomyomas, fibromyomas, fibromas, myofibromas and myomas. They can be small or quite large.

While fibroids can cause a variety of symptoms, they may not cause any symptoms at all-so you may not even know you have one. Heavy bleeding is the most common symptom associated with fibroids and the one that usually prompts a woman to make an appointment with her health care professional. You may learn you have one or more fibroids after having a pelvic exam.

Fibroids may cause a range of other symptoms, too, including pain, pressure in the pelvic region, abnormal bleeding, painful intercourse, frequent urination or infertility. Fibroids usually grow slowly during your reproductive years, but may increase in size with pregnancy. At menopause fibroids shrink because estrogen levels decline. Using menopausal hormone therapy containing estrogen after menopause may cause fibroids to continue to grow and cause symptoms. Progesterone, growth hormone and prolactin are other hormones that may stimulate a fibroid's growth once it has already formed.