Abstract

This population-based case-control study assessed the effect of current use of monophasic or triphasic oral contraceptives (OCs) on the risk of functional ovarian cyst development. The cases were all 15-39-year-old enrollees in the Group Health Cooperative of Puget Sound who had either an inpatient primary diagnosis of functional ovarian cyst in 1988 or 1989 (N = 67) or an outpatient primary diagnosis of functional ovarian cyst from March 1988 through August 1989 at one of five Group Health Cooperative primary care clinics (N = 39). Controls were randomly selected enrollees matched to the cases for age, primary care clinic, and enrollment date (N = 255). Subjects with previous hysterectomy or oophorectomy were excluded from this analysis. Pharmacy and medical record review showed that 16% of cases and 19% of controls were currently using monophasic OCs, whereas 11% of cases and 9% of controls were using triphasic OCs. Compared with women not using hormonal contraception, the relative risks of a diagnosed functional ovarian cyst among women currently using OCs were 0.8 (95% confidence interval [CI] 0.4-1.8) for users of monophasic OCs and 1.3 (95% CI 0.5-3.3) for users of triphasic OCs. In contrast to previous studies of monophasic OCs containing higher steroid dosages, the results of this study suggest that current use of low-dose monophasic OCs does not substantially decrease a woman's risk of functional ovarian cyst formation. In addition, our results do not support recent speculation that current use of triphasic OCs appreciably increases the risk of functional ovarian cysts.