What Are Uterine Fibroids?
Uterine fibroids are lumps that grow on your uterus. You can have fibroids on the inside, on the outside, or in the wall of your uterus. Fibroids are very common in women in their 30s and 40s. But fibroids usually do not cause problems. Many women never even know they have them. Fibroids are the most frequently seen tumors of the female reproductive system.
Fibroids, also known as uterine myomas, leiomyomas, or fibromas, are firm, compact tumors that are made of smooth muscle cells and fibrous connective tissue that develop in the uterus. Symptoms may include heavy periods, cramping, painful sex, and an urge to urinate. Treatment options include hysterectomy, embolization, and hormone therapy.
It is estimated that between 20 to 50 percent of women of reproductive age have fibroids, although not all are diagnosed. Some estimates state that up to 30 to 77 percent of women will develop fibroids sometime during their childbearing years, although only about one-third of these fibroids are large enough to be detected by a health care provider during a physical examination.
In more than 99 percent of fibroid cases, the tumors are benign (non-cancerous). These tumors are not associated with cancer and do not increase a woman’s risk for uterine cancer. They may range in size, from the size of a pea to the size of a softball or small grapefruit.
Doctors are not sure what causes fibroids. But the female hormones estrogen and progesterone seem to make them grow. Your body makes the highest levels of these hormones during the years when you have periods. Your body makes less of these hormones after you stop having periods (menopause). Fibroids usually shrink after menopause and stop causing symptoms.
Women who are approaching menopause are at the greatest risk for fibroids because of their long exposure to high levels of estrogen. Women who are obese and women of African-American heritage also seem to be at an increased risk, although the reasons for this are not clearly understood.
Research has also shown that some factors may protect a woman from developing fibroids. Some studies, of small numbers of women, have indicated that women who have had two live born children have one-half the risk of developing uterine fibroids compared to women who have had no children.
Scientists are not sure whether having children actually protected women from fibroids or whether fibroids were a factor in infertility in women who had no children. The National Institute of Child Health and Human Development are conducting further research on this topic and other factors that may affect the diagnosis and treatment of fibroids.