Endometriosis-related infertility rates fall, but global case numbers keep rising

Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus. It can disrupt fertility through inflammation and changes affecting the ovaries, fallopian tubes and embryo implantation. Yet its global impact on infertility has remained unclear.

A new analysis published in Reproductive and Developmental Medicine reveals a mixed picture: the population rate of endometriosis-related infertility has fallen substantially, but the number of women affected continues to rise.

Based on Global Burden of Disease 2021 (GBD 2021) data, researchers examined estimates for women aged 15 to 49 across 204 countries and territories from 1990 to 2021. The number living with infertility attributed to endometriosis increased by 9.1%, from 1.09 million to 1.19 million. At the same time, the age-standardized prevalence rate fell by about 28%.

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

The analysis also revealed a shift in the type of infertility carrying the greatest burden. Primary infertility, or difficulty achieving a first pregnancy, declined slightly in absolute numbers. Secondary infertility, meaning difficulty becoming pregnant after a previous pregnancy, increased and accounted for most endometriosis-related infertility cases in 2021.

Women aged 25 to 29 consistently represented the largest share of the global burden, while case numbers also rose among women aged 30 to 49. Delayed childbearing, longer exposure to inflammation and age-related declines in ovarian reserve may contribute to these patterns.

Large geographic differences remained. India, China and Indonesia had the greatest numbers of affected women, partly because of their large populations. Rates were generally higher in regions with lower scores on the Sociodemographic Index, which reflects income, education and fertility conditions. Uneven access to diagnosis, fertility services and endometriosis treatment may also shape these differences.

“Endometriosis-related infertility is not a uniform global problem,” Wang said. “Strategies must reflect local healthcare access, reproductive patterns and the growing importance of secondary infertility.”

The findings could help health systems direct reproductive services toward the ages and regions carrying the greatest burden. Earlier recognition of endometriosis, better access to treatment and fertility-preservation counseling, and stronger reproductive healthcare infrastructure may help reduce its impact. Continued monitoring will be important as population growth and later childbearing reshape demand for care.