According to Adam's Medical Encyclopedia:

Uterine fibroids are non-cancerous tumors that develop within or attach to the wall of the uterus, a female reproductive organ.

Alternatives to Hysterectomy warns:

It is generally accepted that fibroids may cause infertility, recurrent pregnancy losses and premature delivery.

An article from Medical News Today tells of treating fibroids with ultrasound:

A noninvasive ultrasound procedure effectively shrinks uterine fibroids and significantly relieves fibroid-related symptoms in women, according to the results of a multicenter clinical trial reported in the June issue of the journal Radiology. Magnetic resonance-guided, focused ultrasound surgery (MRgFUS) allows radiologists to precisely target fibroids without harming healthy surrounding tissue.

The article goes on to say:

Uterine fibroids are benign growths of the muscle inside the uterus. According to the National Institutes of Health, at least 25 percent of women in the United States age 25 to 50 suffer from symptomatic uterine fibroids. Fibroid symptoms can include excessive menstrual bleeding, enlarged uterine size, frequent urination, pelvic pressure or pain and infertility.

Graphics from All About Myomectmy.