Roughly 190 million people worldwide have endometriosis, according to the World Health Organization. That’s about 10% of all women and girls of reproductive age. In the United States alone, researchers estimate at least 6.5 million women are affected, representing 11% or more of women between 15 and 44.
Those numbers are almost certainly undercounts. Endometriosis is notoriously difficult to diagnose, and many people live with it for years before getting answers. The true prevalence is likely higher than any current estimate reflects.
Why the Real Number Is Probably Higher
The biggest reason official estimates fall short is the diagnostic delay. The median time between when symptoms start and when a person receives a confirmed diagnosis is 7 years. In some countries the gap is even wider: Australian data shows an average delay of about 12 years, and French data puts it around 10 years. During all that time, those people have endometriosis but aren’t counted in prevalence statistics that rely on confirmed diagnoses.
Several factors drive this delay. Period pain is often dismissed as normal, both by the people experiencing it and by their doctors. Symptoms overlap with other conditions like irritable bowel syndrome or pelvic inflammatory disease. And for a long time, definitive diagnosis required surgery (laparoscopy), which meant many people with milder symptoms were never formally evaluated. Imaging techniques have improved, but plenty of cases still go undetected without surgery.
Endometriosis in Adolescents
Endometriosis is not just an adult condition. Among adolescents who undergo laparoscopy for chronic pelvic pain, about 64% are found to have endometriosis. That figure comes from a systematic review of 19 studies covering over 1,200 symptomatic teens. The prevalence in individual studies ranged from 25% to 100%, but the overall pattern is clear: when young people have persistent pelvic pain severe enough to warrant investigation, endometriosis is the cause more often than not.
This matters because early diagnosis can help manage symptoms before they progress. Yet teens are especially likely to have their pain minimized or attributed to “normal” periods, which contributes to the years-long diagnostic delays seen across all age groups.
The Link to Infertility
Endometriosis and infertility are closely connected. Approximately 30 to 50% of women with endometriosis experience infertility, and when researchers look at the problem from the other direction, 25 to 50% of women being evaluated for infertility turn out to have endometriosis. In fact, infertility is sometimes the reason endometriosis gets discovered in the first place, particularly in people whose pain symptoms were mild or absent.
The condition can affect fertility in multiple ways. Tissue growing outside the uterus can distort the anatomy of the pelvis, block fallopian tubes, or create an inflammatory environment that makes it harder for an egg to be fertilized or implant. Even early-stage disease, where visible tissue growth is minimal, appears to reduce fertility, though the exact mechanisms are still being studied.
What Happens After Menopause
Most endometriosis symptoms improve after menopause because the condition is fueled by estrogen, which drops significantly during that transition. However, endometriosis doesn’t always disappear entirely. Some postmenopausal women continue to have symptoms or are newly diagnosed, particularly if they use hormone replacement therapy. The medical literature on postmenopausal endometriosis is still limited, and there’s no reliable estimate of how common it is in this group. The 10% global prevalence figure specifically refers to reproductive-age women and doesn’t account for older populations.
The Financial Weight of the Condition
Beyond the physical toll, endometriosis carries a significant economic burden. The total annual cost in the United States, including healthcare expenses and lost productivity from missed work and reduced output, was estimated at $69.4 billion in a 2009 analysis. On an individual level, people with endometriosis spend roughly $13,670 per year on direct healthcare costs, compared to about $5,780 for similar patients without the condition. That translates to an extra $6,470 per year in medical spending attributable to the disease.
These costs reflect the reality of living with endometriosis: frequent doctor visits, imaging, surgeries, medications for pain management, and fertility treatments. Many people also deal with indirect costs that don’t show up in medical billing, like career setbacks from chronic pain or the emotional toll of years spent seeking a diagnosis.
Who Gets Endometriosis
Endometriosis can affect anyone who menstruates, starting from their very first period. It occurs across all racial and ethnic groups, though historically it was studied primarily in white women, which has skewed both awareness and diagnosis patterns. Research increasingly shows that Black and Hispanic women are less likely to be diagnosed, not because they’re less likely to have the condition, but because their symptoms are more frequently dismissed or misattributed.
There is no single known cause. Genetics play a role, as the condition runs in families. But no gene test or blood test can confirm it, and no lifestyle factor reliably prevents it. The combination of invisible symptoms, slow diagnosis, and a condition that can only be definitively confirmed through invasive procedures means that 190 million is best understood as a floor, not a ceiling.