What cause endometrisis? is it only from miscarriage/labor only?

Not quite: Theories on how endometriosis starts include: retrograde menstruation, where menstrual blood containing endometrial cells flows backward through the fallopian tubes and into the pelvis; transformation, where hormones or other factors transform some abdominal lining cells into endometrial-type cells; post-surgical (such as a C-section) where endometrial cells somehow got into the pelvis; etc...