Overview
Polycystic ovary syndrome (PCOS) is one of the most common hormone conditions in women of reproductive age. Global health bodies estimate it affects roughly 1 in 10 women, yet a large share are never formally diagnosed. This page pulls together the most reliable primary data — from the World Health Organization, the U.S. Centers for Disease Control and Prevention (CDC), and the U.S. Office on Women's Health — with the data year attached to every figure.
Before reading any PCOS statistic, one caveat matters more than the rest: different medical groups use different diagnostic rules (the 1990 NIH criteria, the 2003 Rotterdam criteria, and others), so published prevalence estimates vary widely depending on which definition a study used. Higher numbers usually reflect broader criteria, not a different disease. For the wider picture of how PCOS is defined and managed, see our PCOS hub.
| Figure | Estimate | Source (data year) |
|---|---|---|
| Global prevalence, reproductive age | 10-13% of women | WHO (2026) |
| Cases undiagnosed worldwide | Up to 70% | WHO (2026) |
| U.S. women affected | As many as 5 million | CDC (2024) |
| Women aged 15-44 in U.S. | 5-10% (about 1 in 10) | Office on Women's Health (2025) |
| Develop type 2 diabetes by age 40 | More than half | CDC (2024) |
| Affected by excess hair (hirsutism) | Up to 70% | Office on Women's Health (2025) |
How common is it?
As of 2026, the World Health Organization estimates that 10-13% of women of reproductive age worldwide have PCOS, and describes it as the most common cause of anovulation (absent ovulation) and a leading cause of infertility. Strikingly, the WHO notes that up to 70% of affected women remain undiagnosed (2026), which means the true burden is almost certainly under-counted in health records.
U.S. estimates fall in a similar band. As of 2025, the Office on Women's Health puts the figure at 5-10% of women aged 15 to 44 — about 1 in 10 of childbearing age. The CDC estimates PCOS affects as many as 5 million U.S. women (2024). The gap between these ranges is largely a definitions story: narrower NIH criteria produce lower counts, while broader Rotterdam criteria push estimates higher.
Who it affects
Age
PCOS is not only an adult diagnosis. The CDC notes it often develops as young as age 11 or 12, around a girl's first period (2024). In practice, though, most women are diagnosed in their 20s and 30s, once irregular cycles, fertility questions, or metabolic symptoms bring them to a clinician (Office on Women's Health, 2025). Irregular or skipped cycles are one of the most common first clues — our overview of menstrual health explains what a typical cycle looks like.
Ethnicity
The Office on Women's Health states that women of all races and ethnicities are at risk (2025). Where reliable comparative data exist, prevalence does vary somewhat by background. A 2017 systematic review and meta-analysis (Ding and colleagues) found that, under the stricter 1990 NIH criteria, pooled prevalence was about 5.5% in White women, 7.4% in Black women, and 6.1% in Middle Eastern women; under the broader Rotterdam criteria, estimates for Middle Eastern women rose to roughly 16% (2017). Read these numbers cautiously — they reflect the criteria and populations studied, not a fixed ranking.
Related risks
PCOS is closely tied to how the body handles insulin. Many women with PCOS have insulin resistance, and the metabolic fallout is well documented: the CDC reports that more than half of women with PCOS develop type 2 diabetes by age 40 (2024), and the Office on Women's Health frames it as more than half having diabetes or prediabetes before 40 (2025). Because of this, clinicians often monitor blood sugar — you can learn what the numbers mean in our guide to the HbA1c test, and see the wider metabolic picture under weight and metabolism and heart health.
Fertility is the other headline risk. The WHO calls PCOS a leading cause of infertility (2026), while the Office on Women's Health emphasizes that it is one of the most common — but treatable — causes (2025). Excess hair growth (hirsutism) affects up to 70% of women with PCOS (Office on Women's Health, 2025). For symptoms that overlap with other hormone conditions, compare our thyroid health and gynecologic health pages.
Trends
Two patterns stand out over time. First, estimates have widened as diagnostic criteria evolved — the same population can look 5% affected under one rulebook and above 10% under another, which is why the WHO's 10-13% range (2026) sits above older NIH-criteria figures. Second, under-diagnosis remains the dominant gap: the WHO's up-to-70%-undiagnosed estimate (2026) suggests recognition, not incidence, is where most movement is still needed. A Global Burden of Disease analysis of women aged 15-49 estimated that new (incident) PCOS cases rose gradually — roughly 0.56% per year — between 1990 and 2019, with women aged 20-29 the most affected group.
Frequently asked questions
How many women have PCOS?
The WHO estimates 10-13% of women of reproductive age worldwide (2026); in the U.S., the Office on Women's Health puts it at 5-10% of women aged 15-44 (2025), and the CDC at as many as 5 million women (2024).
How often does PCOS go undiagnosed?
Up to 70% of affected women are undiagnosed worldwide, according to the WHO (2026).
Does PCOS raise diabetes risk?
Yes. The CDC reports that more than half of women with PCOS develop type 2 diabetes by age 40 (2024), largely because insulin resistance is common in the condition.
PCOS looks different from person to person, and statistics describe populations, not individuals. If you have irregular periods, unexplained weight changes, or fertility concerns, talk to your clinician about whether testing for PCOS makes sense for you.
