What Causes Fibroids?

Anywhere from 20-40% of women over the age of 35 may be affected by uterine fibroids—noncancerous tumors that grow on or in the muscle wall of the uterus. With so many women affected, you may wonder if you’re one of them.

Although there is no definite cause for uterine fibroids, there are some factors that may increase the risk.


Fibroid growth is largely attributed to the levels of estrogen and progesterone being produced in the body. Estrogen makes the tumors grow and the fibroids themselves contain more hormone receptors than normal uterine muscle.

For this reason, fibroids usually stop growing and shrink once the body reaches menopause and stops producing as much estrogen. In the same way, fibroids often grow faster during the first trimester of pregnancy and then shrink after the birth.


If fibroids run in your family, evidence has shown that you may be more likely to get them yourself. Fibroids have changes in their genetic makeup that are not found in the other muscle in the lining of the uterus, and these changes may be passed down through family members.

If your mother has had fibroids, you are about three times more likely to be affected by them than someone without the genetic ties. In addition, it is more likely for identical twins to both have fibroids than non-identical twins.

Hair relaxers

Women who use hair relaxers may also be more likely to get fibroids. A study done on 23,000 African American women showed that using hair relaxers may be linked to uterine fibroids. More specifically, the scalp burns caused by the relaxers may increase the risk.

The use of hair relaxers has not been proven to cause fibroids. However, the study does show that women who use them have a higher incidence of uterine fibroids. They may also be linked to earlier puberty. Women who get their periods earlier in life may be more prone to fibroids as well.

Other factors

There are a few minor factors that may influence the prevalence and growth of fibroids. Other substances in the body could affect fibroid growth, such as those that help maintain tissues.

Diet and obesity may also be linked to fibroid growth. Very heavy women can be two or three times more likely to be affected by fibroids, and a poor diet can be detrimental as well. Eating dark, leafy greens can help lower the risk.

More information

If you think you may be at risk or affected by fibroids, you can learn more by reading our post How to Know If You Have Uterine Fibroids.

If you do have uterine fibroids and are looking for a solution, explore treatment options here.

PLEASE NOTE: The above information should not be construed as providing specific medical advice, but rather to offer readers information to better understand their lives and health. It is not intended to provide an alternative to professional treatment or to replace the services of a physician.