Characteristics of the menstrual cycle after discontinuation of oral contraceptives.

BACKGROUND Menstrual cycle function may continue to be altered after discontinuation of oral contraceptives (OC). Few studies have been published on the effects of recent OC use on menstrual cycle parameters; none have examined characteristics of the menstrual flow or the quality of cervical mucus. The purpose of this retrospective matched cohort study is to assess biomarkers of the menstrual cycle after discontinuation of OCs. METHODS Among a sample of women who daily recorded observations of menstrual cycle biomarkers, 70 women who had recently discontinued OCs were randomly matched by age and parity with 70 women who had not used OCs for at least 1 year. Outcomes investigated included overall cycle length, length of the luteal phase, estimated day of ovulation, duration of menstrual flow, menstrual intensity, and mucus score. Differences between recent OC users and controls were assessed using random effects modeling. RESULTS Recent OC users had statistically significantly lower scores for mucus quality for cycles 1 and 2. Additionally, OC users had a later estimated day of ovulation that was statistically significant in cycle 2 and a decreased intensity of menstrual flow that was significant in the first four cycles (difference = -0.48 days). In random effects modeling, all these parameters were significantly different for the first six cycles combined. CONCLUSIONS Menstrual cycle biomarkers are altered for at least two cycles after discontinuation of OCs, and this may help explain the temporary decrease in fecundity associated with recent OC use.