Post-partum endometritis is a different condition than endometriosis, although both occur after pregnancy and delivery. When a person is pregnant, bacteria can reach the lining of the uterus and cause an infection. This can occur during vaginal delivery, but also during pregnancy through pelvic examinations, for example. The condition typically develops after delivery, which can be vaginal or via c-section. It affects up to 27% of caesarian births.