What causes fibroids and how common are they?
Since no one knows what causes fibroids, we also don't know why they grow or shrink. We do know that fibroids need the female hormones - estrogen and progesterone - in order to grow. They grow rapidly during pregnancy, when hormone levels are high. They shrink when hormone levels are low and/or anti-hormone medication is used. They also stop growing or shrink once a woman reaches menopause. Medical studies are underway to help shed light on these questions.
There are factors that can increase a woman's risk of developing fibroids, including:
- Age. Fibroids become more common as women age, especially during the 30s and 40s through menopause. After menopause, fibroids usually shrink.
- Family history. Having a family member with fibroids increases your risk. If a woman's mother had fibroids, her risk of having them is about three times higher than average.
- Ethnic origin. Eighty (80) percent of African American women and 70 percent of Caucasian, Hispanic and Asian women develop uterine fibroids by the time they are 50.
- Obesity. Women who are overweight are at higher risk for fibroids. For very heavy women, the risk is two to three times greater than average.
- Eating habits. Eating a lot of red meat (e.g., beef) and ham is linked with a higher risk of fibroids. Eating plenty of green vegetables seems to protect women from developing fibroids.
- In about one third of women who have fibroids, they grow large enough to be detected by a physician during a gynecological exam. Even among these women, 70 percent will never have symptoms or require treatment.