Endometriosis occurs when tissue similar to the lining of your uterus grows outside of it. It affects 1 in 10 women of reproductive age, often causing pain and other symptoms. Here’s what to look out for and how to manage it: Signs & Symptoms: Chronic pelvic pain: Especially around your period. Heavy periods or bleeding between cycles. Pain during or after sex. Painful bowel movements or urination (often during periods). Infertility or difficulty getting pregnant. Fatigue, nausea, and bloating.