Endometriosis-Related Infertility Cases Rise Despite Falling Rates

The global prevalence rate of infertility linked to endometriosis fell by nearly 30% between 1990 and 2021, yet the total number of affected women climbed by 9.1% over the same period, according to an analysis of Global Burden of Disease (GBD) 2021 data published in Reproductive and Developmental Medicine.¹

Using data on 204 countries and territories, researchers estimated that endometriosis-related infertility (EMRI) among women aged 15 to 49 years rose from 1.09 million cases in 1990 to 1.19 million in 2021. Over that period, the global all-age prevalence rate declined from 42.52 to 30.16 per 100,000 women, a 29.07% drop, while the age-standardized prevalence rate fell 28.38%.

Secondary Infertility Emerges as the Larger Concern

The shift was not uniform across infertility subtypes. Primary infertility—difficulty achieving a first pregnancy—declined slightly, from 0.32 million to 0.31 million cases, whereas secondary infertility, or difficulty conceiving after a prior pregnancy or birth, rose from 0.77 million to 0.87 million cases. Secondary infertility was already the larger subtype in 1990 and accounted for an even greater share of the total by 2021. The annual net drift for primary infertility was −1.43%, nearly double the −0.75% rate for secondary infertility, indicating that secondary infertility is declining far more slowly.

“The declining rate is encouraging, but the continued rise in case numbers shows that progress has not reduced the overall demand for care," Wen-Wen Wang, the study’s corresponding author, said in a statement.² "Population growth and changing reproductive patterns must be considered alongside improvements in diagnosis and treatment."

Younger Women Carry the Largest Share, but the Burden Is Shifting Older

Women aged 25 to 29 years represented the largest share of EMRI cases throughout the study period. Still, incidence rose between 1990 and 2021 among women aged 30 to 34, 35 to 39, 40 to 44, and 45 to 49 years, a pattern the authors linked to delayed childbearing, prolonged inflammatory exposure, and age-related declines in ovarian reserve.

The largest declines in primary infertility occurred among women younger than 30 years, whereas the steepest declines in secondary infertility were concentrated among women older than 30, particularly in low- and low-middle-sociodemographic index (SDI) regions.

Regional Gaps Remain Wide

National burden tracked closely with population size: India, China, and Indonesia reported the highest EMRI case counts in 2021, at 240,000, 150,000, and 57,000, respectively. China's case count fell 31.65% from 1990, while India's and Indonesia's rose 14.40% and 16.55%. Qatar, Niger, and the United Arab Emirates posted the steepest case increases (358.43%, 222.91%, and 191.90%, respectively), and the Solomon Islands, Niger, and Papua New Guinea reported the highest all-age infertility rates in 2021.

By contrast, the lowest all-age infertility rates were reported in Portugal (12.7 per 100,000), Denmark (13.2), and Spain (13.4), while low-middle SDI countries recorded the sharpest overall declines, with age-standardized rate reductions of 46.07% for primary infertility and 37.22% for secondary infertility. High-SDI regions saw infertility risk begin rising again after 2005, a trend the authors attributed largely to secondary infertility.

The findings arrive as the World Health Organization develops its first global clinical guideline on endometriosis, an effort prompted by persistent delays in diagnosis and uneven access to specialized care worldwide.³

Wang noted that interventions will need to reflect that unevenness, stating that "endometriosis-related infertility is not a uniform global problem. Strategies must reflect local health care access, reproductive patterns, and the growing importance of secondary infertility.”²

References

1. Yan Q, Liu F, Wei J, Xiang T, Ren W, Wang WW. Global, regional, and national burden of endometriosis-related infertility in women of reproductive age: analysis based on the Global Burden of Disease Study 2021. Reprod Dev Med. 2026;10(3):184-193. doi:10.1097/RD9.0000000000000160
2. Endometriosis-related infertility rates fall, but global case numbers keep rising. News release. Shanghai Jiao Tong University Journal Center. September 6, 2026. Accessed September 18, 2026. https://www.eurekalert.org/news-releases/1142877
3. Call for experts: new WHO guideline on endometriosis. WHO. April 9, 2026. Accessed September 18, 2026. https://www.who.int/news-room/articles-detail/call-for-experts-for-the-new-who-guideline-on-endometriosis