Uterine Fibroids

What Uterine Fibroids Are

Researchers describe fibroids as benign tumors made of smooth muscle cells and fibroblasts, held together by a substantial amount of fibrous extracellular matrix.^[2] A fibroid grows from a single cell line that starts dividing out of control, which is why the medical literature calls it a monoclonal, or clonal, growth.^[1] Fibroids vary enormously in size, number, and location within the uterus, and that variation is a big part of why they're described as heterogeneous, ranging from tiny growths that never cause a symptom to large ones tied to substantial bleeding and pain.^[2]

How Common They Are

Fibroids are the most common benign tumor of the reproductive tract.^[1] A widely cited study of 1,364 women aged 35 to 49 used ultrasound screening for premenopausal participants, rather than relying on which women reported symptoms, and found the cumulative incidence by age 50 was more than 80% among Black women and nearly 70% among white women.^[3] That racial gap tracks with a broader pattern in the research: Black women tend to develop fibroids earlier in life and to develop more severe forms of the disease.^[2]

What People With Fibroids Commonly Track

The literature ties fibroids to abnormal uterine bleeding, heavy menstrual bleeding, pelvic pain and pressure, and bladder or bowel symptoms, with which symptoms show up depending heavily on a fibroid's size and location.^[1] Fibroids that sit just under the uterine lining, called submucosal fibroids, are more likely to disrupt normal bleeding and can cause heavy bleeding even when small. Larger fibroids that bulge outward are more likely to press on nearby organs instead, with fibroids toward the front of the uterus more often tied to pelvic pressure and bladder symptoms and fibroids toward the back more often tied to constipation.^[1]

Because of that bleeding link, people navigating a fibroid diagnosis often keep a day-by-day record of heavy menstrual bleeding and period flow, alongside cramps and where pelvic pain shows up across the cycle rather than just on period days. Heavy, recurring blood loss also affects iron status: a 2026 claims-based study that compared large matched cohorts of women found anemia developed in about a third of those with both fibroids and heavy menstrual bleeding, compared with 4.4% of women with neither.^[4] That's the mechanism that makes flow logs worth reading alongside a lab result like ferritin.

How Go Go Gaia Supports Tracking It

Go Go Gaia logs period flow, cramps, and pelvic pain each with their own 1-click entry, timestamped and charted against your cycle day. If you upload lab results like ferritin, the app charts those values on the same timeline, so a heavy-flow stretch and a lab draw show up side by side instead of living in separate places.

What the Research Shows

Screening-based research puts the lifetime chance of developing a fibroid well above what symptom-based counts alone would suggest. In the ultrasound-based cohort described above, cumulative incidence by age 50 reached more than 80% for Black women and nearly 70% for white women, regardless of whether those women had ever reported a symptom.^[3]

Fibroids account for one-third to half of all hysterectomies performed in the United States, and roughly three-quarters of fibroid treatments are hysterectomies, a measure of how much of the disease's burden comes from its more symptomatic cases.^[2]

A 2026 study using insurance claims data compared three matched cohorts of 22,057 women each and found anemia developed in about a third of women with both fibroids and heavy menstrual bleeding, compared with 4.4% of the comparison group with neither. Women who developed anemia went on to have substantially higher rates of hysterectomy and blood transfusion than those who didn't.^[4]

Related Terms

Frequently Asked Questions

Educational information based on published sources. Not medical advice. For personal concerns, please consult your doctor.

How common are uterine fibroids?

Very common. A widely cited study of 1,364 women aged 35 to 49, which used ultrasound screening for premenopausal participants rather than relying on reported symptoms, found the cumulative incidence by age 50 was more than 80% among Black women and nearly 70% among white women.^[3]

Do all uterine fibroids cause symptoms?

No. Fibroids vary enormously in size, number, and location, and researchers describe their clinical presentation as ranging from no symptoms at all to substantial bleeding and pain. When symptoms occur, they're most often abnormal or heavy bleeding, pelvic pain and pressure, and bladder or bowel symptoms tied to where a fibroid sits.^[1][2]

Why do people with fibroids track iron-related labs like ferritin?

Heavy, recurring blood loss affects iron status. A 2026 claims-based study found anemia developed in about a third of women who had both fibroids and heavy menstrual bleeding, compared with 4.4% of women with neither, which is why flow logs and iron-panel results are often read together.^[4]