Black women develop uterine fibroids at roughly three times the rate of white women, and by age 50, more than 80% will have them. The disparity isn’t explained by any single cause. Instead, it reflects a combination of genetics, hormone biology, vitamin D levels, environmental exposures, and gaps in healthcare access that compound one another.
How Large Is the Disparity?
Ultrasound studies show that over 80% of Black women and about 70% of white women will develop fibroids by age 50. But that top-line comparison understates the gap. Black women have a threefold higher age-adjusted incidence rate even after researchers control for other risk factors like weight, age, and family history. They’re also diagnosed earlier in life, tend to develop larger and more numerous fibroids, and report more severe symptoms including heavy bleeding, pelvic pain, and pressure on the bladder.
These differences carry into treatment outcomes. Black women are two to three times more likely to undergo a hysterectomy for fibroids than women in other racial groups. They also face higher rates of recurrence after less invasive procedures, which can mean repeated surgeries over a lifetime.
Genetics and Fibroid Growth
Fibroid tissue frequently carries mutations in a gene called MED12, which helps regulate cell growth. In one study of fibroid samples from South African patients, half of the tumors had a MED12 mutation. These mutations appear across racial groups, but certain genetic factors may make fibroids grow faster or larger in women of African descent.
One example involves the estrogen receptor. Fibroids are hormone-responsive tumors, meaning estrogen and progesterone fuel their growth. Black women have a higher prevalence of a specific estrogen receptor variant that has been linked to increased fibroid risk in multiple studies. This doesn’t mean the gene causes fibroids on its own, but it may lower the threshold for tumor development and make fibroids more responsive to hormonal signals throughout reproductive life.
Beyond individual genes, researchers at the National Institutes of Health have found that DNA methylation patterns, which are chemical tags on DNA that turn genes on or off without changing the DNA sequence itself, differ between fibroid tissue from Black and white women. These epigenetic differences could help explain why fibroids in Black women tend to behave more aggressively, growing faster and causing more symptoms, even when the underlying tumor type looks similar under a microscope.
The Vitamin D Connection
Black women are 10 times more likely to be vitamin D deficient than white women. Darker skin contains more melanin, which filters ultraviolet light and slows the skin’s ability to produce vitamin D from sunlight. This biological reality has measurable consequences for fibroid risk.
Lab studies have shown that vitamin D directly inhibits the growth of fibroid cells. It slows their proliferation, triggers programmed cell death in fibroid tissue, and acts as an anti-fibrotic agent, meaning it works against the stiff, fibrous tissue that gives fibroids their structure. In animal models, vitamin D treatment reduced fibroid tumor size. Black women in these studies consistently had lower blood levels of vitamin D compared to white women, which may remove a natural brake on fibroid development.
This doesn’t mean vitamin D supplements will shrink existing fibroids, but the connection is strong enough that researchers consider it a meaningful piece of the disparity puzzle.
Environmental and Chemical Exposures
Hair relaxers and chemical straighteners, products used disproportionately by Black women, contain phthalates, parabens, and other endocrine-disrupting chemicals. These compounds can interfere with the body’s hormone signaling, mimicking estrogen or blocking its normal regulation. Since fibroids depend on estrogen to grow, chronic exposure to these chemicals may create a hormonal environment that favors fibroid development.
The exposure often starts early. Many Black girls begin using chemical hair products in childhood or adolescence, which means decades of repeated contact with these compounds during the reproductive years when fibroids are most likely to form. A large ongoing study of Black women’s health has examined this link specifically, finding associations between long-term relaxer use and increased cancer risk in reproductive organs. The same endocrine-disrupting mechanism is relevant to fibroid growth.
Diet and Protective Factors
Dietary patterns also play a role. In a large study of Black women, those who consumed four or more servings of dairy per day had a 41% lower rate of fibroid development compared to women who ate less than one serving daily. The protective effect held up even after researchers controlled for genetic ancestry, ruling out the possibility that it was simply a marker for mixed-race heritage or other confounding factors. The trend was consistent: more dairy, lower risk, with a statistically significant dose-response relationship.
The mechanism likely involves calcium and vitamin D (dairy is a primary dietary source of both), along with a protein in milk called butyrate that has anti-proliferative properties. For Black women who are already more likely to be vitamin D deficient and lactose intolerant, lower dairy consumption may remove one more layer of protection against fibroid growth.
Healthcare Gaps That Worsen Outcomes
Biology doesn’t act in a vacuum. Black women are more likely to have their fibroid symptoms dismissed by providers, report negative experiences within the healthcare system, and wait longer to see a specialist. This delays both diagnosis and treatment, which means fibroids have more time to grow before any intervention begins.
By the time Black women receive a diagnosis, their fibroids tend to be larger and more numerous, which limits treatment options. Smaller fibroids can often be managed with medication or minimally invasive procedures, but larger ones may require surgery. The higher hysterectomy rate among Black women is partly a downstream consequence of later diagnosis: when fibroids are caught at a more advanced stage, the most conservative options are sometimes no longer on the table.
Recurrence compounds the problem. Fibroids frequently return after removal, and each recurrence means another round of imaging, decision-making, and potentially surgery. For women navigating a system that was slow to take their symptoms seriously in the first place, this cycle can be especially burdensome.