CONTRACEPTIVE METHODS AND RISK OF PELVIC ENDOMETRIOSIS

The relation between contraceptive methods and risk of pelvic endometr iosis has been analyzed in a case-control study. Cases were 376 women with laparoscopically or laparotomically confirmed pelvic endometriosi s admitted to a network of Obstetrics and Gynecology Clinics in Lombar dy, Northern Italy. Controls were 522 women admitted for acute non-gyn ecological and non-obstetrics conditions to the same hospitals where c ases had been identified. A total 153 women (40.3%) out of the 377 cas es and 254 (29.7%) out of the 522 controls reported ever oral contrace ptive (OC) use: the corresponding relative risk (RR) was 1.6 (95% conf idence interval, CI, 1.2-2.2). The risk was restricted to ex-OC users (RR 1.7, 95% CI 1.3-2.4), the estimated RR for current users being 0.8 (95% CI 0.5-2.9). No clear relation emerged with duration, recency an d latency of OC use and risk of endometriosis. In comparison with neve r IUD users, the risk for ever users was 1.3 (95% CI 0.6-2.8), and no clear relation emerged with duration of use. Likewise, no association was observed between barrier method of contraception and risk of endom etriosis (RR ever vs never users 0.5, 95% CI 0.3-2.4). The role of sel ection and other biases should be considered in the interpretation of epidemiological data on the role of OC on the risk of endometriosis.