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How many people are affected by or at risk for endometriosis?

It is difficult to know exactly how many women have endometriosis because some women might have the condition but not the symptoms. In 2011, the NICHD-led Endometriosis: Natural History, Diagnosis, and Outcomes Study found that the number of women with endometriosis varied depending on the population of women being studied and the diagnostic measures that are used.1

The study found that 11% of a group of women who had not been diagnosed with endometriosis actually had the disorder. If this finding applies to all the women in the United States, the number of American women with endometriosis may well exceed previous estimates of 5 million.

Endometriosis is most common in women in their 30s and 40s,2 but it can affect any female who menstruates.

  • Factors that May Increase the Risk of Endometriosis

  • Factors that May Lower the Risk of Endometriosis


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  1. Buck Louis, G. M., Hediger, M. L., Peterson, C. M., Croughan, M., Sundaram, R., Stanford, J., et al. (2011). Estimated incidence of endometriosis by diagnostic method and study population: The ENDO Study. Fertility and Sterility, 96(2), 360–365. Retrieved August 17, 2016, from [top]
  2. American College of Obstetricians and Gynecologists. (2011). Endometriosis. Retrieved December 10, 2015, from External Web Site Policy [top]
  3. American College of Obstetricians and Gynecologists. (2010). Management of endometriosis (Practice Bulletin No. 114). Obstetrics & Gynecology, 116(1), 223–236. [top]
  4. Treloar, S. A., Bell, T. A., Nagle, C. M., Purdie, D. M., & Green, A. C. (2010). Early menstrual characteristics associated with subsequent diagnosis of endometriosis. American Journal of Obstetrics & Gynecology, 202, 534.e1–534.e6. [top]

What causes endometriosis?

How many people are affected by or at risk for endometriosis?​​​

What are the symptoms of endometriosis?

How do health care providers diagnose endometriosis?​

What are the treatments for endometriosis?​​​​