What Causes Fibroids: The Known Risk Factors
Uterine fibroids, also known as leiomyomas, are the most common benign pelvic tumor in pre-menopausal women. According to the American Society for Reproductive Medicine, uterine fibroids will affect 8 in 10 African American women and 7 in 10 Caucasian women before menopause.
Despite the prevalence of the condition and the plethora of studies that have sought to explain it, the cause of fibroids is still not fully understood. However, evidence suggests that fibroids’ development can be attributed to a combination of genetic and hormonal traits.
Hormonal Risk Factors
The link between fibroids and hormones is well documented. Specifically, it is known that fibroids are estrogen-dependent. As a result, fibroids grow during a woman’s childbearing years, while the ovaries are naturally producing estrogen, and they typically shrink after the onset of menopause, when levels of the hormone drop. The influence of hormones on fibroid growth renders the following traits “risk factors”:
Age – The risk of fibroids increases with age, up to the point of menopause. Once menopause is reached and the body’s estrogen production naturally declines, fibroids typically shrink and – in many cases – disappear entirely.
Contraceptive use – Women who began taking oral contraceptives before the age of 16 are at a greater risk of developing fibroids. However, studies have revealed that using progestin-only injectable contraceptives is associated with a reduced risk of fibroids.
Obesity – Researchers believe that being obese increases the risk of uterine fibroid development, possibly due to the association between obesity and high circulating estrogen levels.
Genetic Risk Factors
Race – The connection between race and fibroids isn’t entirely understood, but an abundance of clinical data shows it to be a significant risk factor. Black women are nearly three times more likely to develop fibroids than white women. Furthermore, research has shown that black women tend to have larger and more symptomatic fibroids than women of other races.
Family health history – Researchers and medical practitioners have long observed a familial predisposition to fibroids. To date, various clinical studies have identified over 100 specific genes as having potential links to fibroid development. OB-GYN Dr. Donald Galen frequently observes the genetic trend in his fibroid patients: “It is common for a woman with fibroids to have a history of her mother, maternal aunt, or sister who also have fibroids, ” he says.
Other Risk Factors
Certain lifestyle and environmental traits have been thought to play a role in the development of fibroids, though clinical studies have yielded somewhat contradictory results.
Diet – Research has shown that women who eat a vegetarian diet are less likely to develop fibroids than women whose diets include meat. Some studies suggest that consuming more fruits, vegetables, and low-fat dairy products could reduce the risk of developing fibroids; however, the effectiveness of changing dietary habits in slowing the growth of existing fibroids or preventing the development of new fibroids has not been conclusively established.
While the exact cause of fibroids remains unclear, existing research points to a confluence of genetic and hormonal traits. Given the prevalence of the condition of uterine fibroids, its epidemiology will undoubtedly continue to be the subject of research. The risk factors that have been established, however, help us to understand who is susceptible to developing fibroids and what physical and lifestyle changes may prevent or minimize fibroids’ occurrence.
- American Society for Reproductive Medicine, “Fibroid Tumor Video Transcript”, ReproductiveFacts.org: 2011.
- Retrieved July 13, 2015, from http://www.reproductivefacts.org/Fibroid_tumor_video/
- Stewart, E. “Uterine Fibroids”, New England Journal of Medicine. 2015; 372: 1646-55.
- Wise, L. et al. “Age-Specific Incidence Rates for Self-Reported Uterine Leiomyomata in the Black Women’s Health Study”, Obstetrics & Gynecology. Mar 2005; 105(3): 563–568.
- Levy, B., “Modern management of uterine fibroids”, Acta Obstetricia et Gynecologica. April 2008; 87: 812-823
- Burbank, F. Fibroids, Menstruation, Childbirth, and Evolution, pp. 89-90. Wheatmark, 2009. Tucson, AZ.