Fibroids are tumors made of smooth muscle cells and fibrous connective tissue. They develop in the uterus. It is estimated that 70 to 80 percent of women will develop fibroids in their lifetime — however, not everyone will develop symptoms or require treatment. The cause of fibroids is not well understood. Risk factors include a family history of fibroids, obesity, or early onset of puberty.
Symptoms include heavy menstrual bleeding, prolonged periods, and pelvic pain. In some cases, there are no symptoms.