Understanding Endometriosis and Its Impact on Fertility Endometriosis is a common condition that affects up to 1 in 10 people of reproductive age , and it can have a significant impact on fertility. Many people live with endometriosis for years before getting a diagnosis — but with the right care and treatment, pregnancy is absolutely possible. 1. What Is Endometriosis? Endometriosis happens when tissue similar to the lining of the uterus (the endometrium) grows outside the