Fibroids are lumps or tumors that grow in the wall of the uterus. Fibroids can be single or multiple, are most often noncancerous and can vary in size, according to the Office on Women’s Health. In rare cases, tumors can grow very large and cause the abdomen to enlarge conspicuously.
The cause of fibroids is uncertain, as of 2015, but researchers attribute their growth to the female hormones estrogen and progesterone. The tumors develop rapidly when hormone levels are high, and they shrink when antihormone drugs are used or when a woman reaches menopause, states the Office on Women's Health.
Fibroids are common to women between the ages of 30 and 50. Some women may experience symptoms such as heavy bleeding, frequent urination, painful sex, lower abdominal enlargement and reproductive problems. Women with a family history of fibroids, African American women, overweight women or women who eat plenty of red meat have a higher risk of developing the tumors, claims the Office on Women's Health.