Endometrial tissue normally grows inside the uterus to support a fertilized egg. In endometriosis, this tissue grows outside the uterus—on the ovaries, fallopian tubes, or other pelvic structures. These abnormal growths can affect fertility by altering the shape and function of the fallopian tubes and by forming ovarian cysts called endometriomas, which interfere with healthy follicle development. The good news is that effective treatments are available to help manage symptoms and improve fertility.