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 microg ethinyl estradiol monophasic OCs (OR 0.69; 95% CI 0.44, 1.10) was slightly lower than that associated with less than 35 microg 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.