Objective: To compare the effects of the contraceptive patch to oral contraceptives (OCs) on follicular size and incidence of ovulation in normal cycles and after dosing errors.
Design: Randomized, open-label.
Setting: Twelve centers.
Patient(s): One hundred twenty-four ovulatory women.
Intervention(s): Subjects received either the patch (groups 1 and 2) or one of three OCs. Correct dosing occurred in cycles 1, 2, 3, and 5. The following dosing errors were planned during cycle 4, a shortened 10-day cycle: [1] patch group 1 subjects wore one patch for 10 consecutive days; [2] for patch group 2 and OC subjects, 7 dosing days were followed by 3 drug-free days.
Main outcome measure(s): Follicular size, as determined at each cycle by the maximum mean follicular diameter.
Result(s): After a 3-day dosing error, follicular size was significantly smaller in the patch group (mean, 7.0 mm) vs. each OC group (range of means, 11.8-17.1 mm). Similar results were seen after proper dosing. The incidence of ovulation was significantly lower for the patch users than for women using OCs.
Conclusion(s): Follicular size and incidence of ovulation were significantly reduced among contraceptive patch users compared with women using OCs in normal cycles and after planned dosing errors.