Endometriosis: Epidemiology, and Etiological Factors

Age is the main determinant of risk of endometriosis. The condition is rare before the menarche, probably increases with age until menopause and decreases after the menopause. The role of menstrual factors as determinants of endometriosis risk has been suggested, women with early menarche, short and heavy menstrual cycles being at higher risk. This has been generally explained by the reflux hypothesis. Parity is inversely associated with the risk of endometriosis, but it is difficult to define if nulliparity is a cause or a consequence of endometriosis. In some studies, the risk of the disease was lower among current oral contraceptive users, but higher in ex-users. However, these different findings may be due to selective mechanisms and indication bias. Other reported risk factors are family history of endometriosis, smoking, alcohol and coffee drinking, a diet rich in saturated fats, overweight (inverse relation), dioxin exposure, personal history of immune disorders.