Unscheduled bleeding with continuous oral contraceptive pills: a comparison of progestin dose

Background: Although the use of continuous oral contraceptive pills (OCPs) eliminates scheduled uterine bleeding, unscheduled bleeding is common. The objective of this study was to determine whether progestin dose influences bleeding with use of continuous OCPs.

Study design: This was a secondary data analysis of two other studies of continuous OCPs. Women were eligible if they were switching from a cyclic hormonal contraceptive to a continuous OCP. Women took a 20-mcg ethinyl estradiol (EE)/100-mcg levonorgestrel (LNG) pill or a 20-mcg EE/90-mcg LNG pill for 112 days. The number of bleeding/spotting days was compared between groups using a t test. Sample size was adequate to detect a difference of 8 days of bleeding/spotting over the 112 day study period (β=0.80, α=0.05).

Results: Sixty-six subjects were enrolled, 33 in each group. There were no differences in baseline characteristic, missed OCPs or side effects. There were no differences in the mean number of bleeding/spotting days in the first 84 days of the study (90 mcg LNG mean 20.8 (SE 3.6) days versus 100 mcg LNG 17.8 (SE 2.3) days, p=.48), nor was there a difference in the time to amenorrhea (p=.35).

Conclusion: Our results do not support the use of one LNG dose over another to decrease the amount of unscheduled bleeding women experience when initiating a continuous OCP.