Fibroids are common non-cancerous (benign) growths of the muscle wall of the uterus. More than 75 percent of women can be found to have small fibroids using MRI, a very sensitive imaging technique. However, only about 30 percent of all women will have fibroids large enough to be noted during a pelvic exam, and the vast majority of even these women, more then 80 percent, will never have symptoms and will never require treatment. It is very likely that the cause of fibroids relates to genes there may also be environmental causes that stimulate fibroid growth.