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Ovulation and follicular development associated with three low-dose oral contraceptives: a randomized controlled
D A Grimes1, A J Godwin, A Rubin
1Department of Obstetrics and Gynecology, University of Southern California School of Medicine, Los Angeles.
Objective:
To address the hypothesis that multiphasic oral contraceptives (OCs) increase rather than decrease the risk of functional ovarian cysts.
Methods:
In this single-center, randomized controlled study, women were assigned to a multiphasic pill, a lower-dose monophasic pill, a higher-dose monophasic pill, or nonsteroidal contraception. Forty volunteers were randomized (ten each) to three different pill regimens or to nonsteroidal contraception. During 6 months of treatment, follicular development was measured by vaginal ultrasonography and ovulation was indicated by serum progesterone levels.
Results:
The relative risk (RR) of developing a follicular structure greater than 30 mm in diameter during a cycle with the higher-dose monophasic pill was 0.5 (95% confidence interval [CI] 0.1-1.9; P = .49) compared with the multiphasic pill. The risk with the lower-dose monophasic pill was comparable to that with the multiphasic pill (RR 1.3, 95% CI 0.5-3.6; P = .56). With the multiphasic pill, the maximum ovulation rate over 60 cycles was 1.7 per 100 cycles (95% CI 0.0-8.9).
Conclusion:
This multiphasic pill more closely resembled the lower-dose monophasic pill than the higher-dose monophasic pill in its suppression of follicular development.