Uterine fibroids are extremely common. They affect up to 70% of women by age 50, making them the most common benign tumor of the uterus. Despite how frequently they occur, many women don’t know they have them because fibroids often cause no symptoms at all.
Lifetime Risk by the Numbers
The most reliable estimates come from ultrasound-based studies that screen women regardless of symptoms. One landmark study found ultrasound evidence of fibroids in over 50% of women aged 35 to 49 who had never been diagnosed. By age 50, the cumulative incidence exceeded 80% in Black women and 70% in white women. These numbers are higher than most people expect because fibroids are frequently missed when there’s no reason to look for them.
Globally, about 120 million women were living with fibroids in 2021, up from roughly 66 million in 1990. That increase largely reflects population growth and better detection rather than a true rise in risk. The rate of fibroids per 100,000 women has stayed relatively flat over three decades.
Most Fibroids Never Cause Symptoms
At least half of all fibroids are asymptomatic, and the true proportion is likely higher. That estimate comes from women whose fibroids were found incidentally during unrelated procedures like cervical screening. Population-wide ultrasound studies consistently find more fibroids than symptom-based diagnoses would suggest, meaning many women carry fibroids their entire lives without ever knowing.
When fibroids do cause problems, the most common issues are heavy or prolonged menstrual bleeding, pelvic pain or pressure, and in some cases, difficulty getting or staying pregnant. Roughly 50 to 75% of fibroids are considered clinically irrelevant because they produce none of these symptoms. Among women who are diagnosed, though, the impact can be significant: about 71% use medication for symptom relief, and 30% eventually undergo a surgical or procedural treatment.
Race and Age of Onset
The disparity between Black and white women is one of the most striking patterns in fibroid research. Black women develop fibroids more often, at younger ages, and with greater severity. In a study of women undergoing hysterectomy for noncancerous conditions, 89% of Black women had fibroids compared to 59% of white women. The average age at diagnosis was 37.5 for Black women versus 41.6 for white women.
Even among young women aged 18 to 30, a pilot ultrasound study found fibroids in 26% of Black participants compared to 7% of white participants. The Black Women’s Health Study reported that roughly 3% of premenopausal Black women receive a new fibroid diagnosis each year, a rate more than double what’s seen in broader populations. These differences are not fully explained by known risk factors and remain an active area of investigation.
Why So Many Go Undetected
Transvaginal ultrasound is the standard first-line tool for diagnosing fibroids, and it’s very good at ruling them out. Its specificity is about 95%, meaning a negative result is highly reliable. But its sensitivity for detecting fibroids is only around 47%, which means it misses roughly half of fibroids that are actually present, particularly small ones or those embedded deep in the uterine wall. This gap between detection and reality is a major reason prevalence numbers vary so widely across studies. Women who are screened with more advanced imaging or who undergo surgery consistently show higher fibroid rates than those diagnosed through ultrasound alone.
Geographic Variation
Fibroid rates differ substantially around the world, though some of this reflects differences in healthcare access and diagnostic practices rather than true biological variation. Eastern Europe consistently reports the highest rates, with countries like Latvia, Russia, and Ukraine at the top. South Asia has the highest overall disease burden when accounting for population size. Australia and New Zealand report the lowest rates globally, with incidence roughly eight times lower than the highest-burden countries.
Trends are also shifting in different directions depending on the region. North America, East Asia, and tropical Latin America are seeing notable increases in both new diagnoses and symptom burden. Western Europe, the Caribbean, and parts of Latin America are trending downward. Sub-Saharan Africa and Southeast Asia have remained relatively stable.
What Increases Your Risk
Age is the strongest predictor. Fibroids are rare before puberty and uncommon in the early twenties, then climb steadily through the thirties and forties before typically shrinking after menopause when estrogen and progesterone levels drop. Race plays a significant independent role, as outlined above. Higher body weight is also consistently linked to greater fibroid risk, likely because fat tissue produces estrogen, which fuels fibroid growth. Starting menstruation at a younger age, having no prior pregnancies, and having a family history of fibroids all increase the likelihood as well.
On the protective side, each pregnancy appears to reduce risk, and long-term use of hormonal contraceptives has been associated with lower rates in some studies. These factors don’t guarantee you will or won’t develop fibroids, but they help explain why prevalence varies so much from person to person.