Oral contraceptives, tubal sterilization, and functional ovarian cyst risk

Objective To determine whether current contraceptive method affects functional ovarian cyst risk, with emphasis on oral contraceptives (OCs) and tubal sterilization. Methods We conducted a case–control study of 18–39-year-old health maintenance organization enrollees with a functional ovarian cyst diagnosed between January 1, and June 30, 1994, and age-matched female controls randomly selected from enrollment files. In-person interviews as well as medical and pharmacy records were obtained for 78% of cases and 82% of controls; these analyses were based on 392 cases and 623 controls. Odds ratios (ORs) calculated with unconditional logistic regression were used to estimate the risk of a functional ovarian cyst diagnosis associated with current contraceptive method. Results In multivariable analyses adjusting for age, education, number of live births, and reference year, the overall OR was 0.72 (95% confidence interval [CI] 0.53, 0.99) for current OC use, compared with use of nonsurgical nonhormonal contraception or no contraception. The risk associated with use of 35 μg ethinyl estradiol monophasic OCs (OR 0.69; 95% CI 0.44, 1.10) was slightly lower than that associated with less than 35 μg ethinyl estradiol monophasic (OR 0.79; 95% CI 0.43, 1.47) or multiphasic OCs (OR 0.76; 95% CI 0.49, 1.19). Women with tubal sterilization had a substantially increased risk of a functional ovarian cyst diagnosis (OR 1.70; 95% CI 1.05, 2.75) compared with women using nonhormonal or no contraception. Conclusion Our findings suggest that low-dose OC use has little or no effect on functional ovarian cyst likelihood. The increased risks we found associated with tubal sterilization merit further investigation.