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Fibroids: Symptoms and Risk Factors

Fibroids are benign overgrowths in the muscle layer of the uterus. They are very common, present in at least one–quarter of women by the age of 40.

There is no identifiable cause of fibroids. However, estrogen is known to be necessary for their growth, as many grow during pregnancy (a period of high estrogen levels) and then recede at menopause (when estrogen levels fall).

Complications of pregnancy are more common in women with fibroids, including miscarriage, abnormal separation of the placenta from the uterus (placental abruption), and premature labor.


Most cases of fibroids have no symptoms. However, they sometimes cause vaginal bleeding, prolonged or heavy menstrual flow, painful menstrual cycles, anemia, urinary complaints, constipation, painful sexual intercourse, or abdominal tenderness.

Risk Factors

African–American women are up to three times more likely to have fibroids compared with white women, and often have more severe disease at a younger age.

  • Age: Fibroids occur during the reproductive years, most commonly during the fourth and fifth decades of life. They do not occur in prepubescent girls and usually shrink at menopause.
  • Genetics: Twins have a greater risk of fibroids when one twin is affected.
  • Pregnancy: Women who have given birth appear to have a decreased risk of fibroids.
Fibroids: Diagnosis and Treatment >>