Amenorrhea frequency with continuous combined hormone replacement therapy: a retrospective analysis. Menopause Study Group.

Objectives: The study retrospectively determined in postmenopausal women the cumulative amenorrhea patterns with continuous conjugated equine estrogens (CE) with or without continuous medroxyprogesterone acetate (MPA), and withdrawal bleeding patterns with cyclic therapy.

Methods: During a 1-year, prospective trial, all patients took CE. Groups A and B also took continuous MPA 2.5 and 5 mg, respectively, C and D took MPA 5 and 10 mg for the last 14 cycle days, respectively, and E took placebo to match MPA.

Results: By cycle 7, 40.4, 52.6 and 53.8% of women in Groups A, B and E, respectively, became amenorrheic. Percentages increased at each subsequent cycle. Of the remaining women in Groups A and B, 42.1 and 46.2%, respectively, experienced only spotting at cycle 7. In Groups C and D, 80 and 65.9%, respectively, had a mean change of equal to or less than 3 days in the onset of withdrawal bleeding/spotting from cycle to cycle for all 13 evaluable cycles.

Conclusions: Amenorrhea is often desirable, and a continuous combined daily regimen of CE 0.625 mg + MPA 2.5 or 5 mg, which resulted in progressive increases in amenorrheic frequency during the 1-year treatment period, may promote compliance. In some women, however, the cyclic regimens, which produced fairly predictable withdrawal bleeding, may be preferable.