Objective: To study progestin administration at less than monthly intervals in postmenopausal women given continuous estrogen replacement.
Methods: Eighty postmenopausal women received 0.625 mg/day of conjugated equine estrogens for 48 weeks. Using a double-masked design, the subjects were randomized to medroxyprogesterone acetate 10 mg/day for 14 days every 28 or 84 days, or the same dosage for 28 of 84 days. Bleeding patterns, endometrial histology, and serum lipids were assessed.
Results: The total days of bleeding during the 48-week study were significantly reduced (P<.05) in the women given the progestin for 14 days every 3 months (mean ± standard deviation 29 ± 16 days) than with the other two regimens. In all groups, secretory endometrium was reported in 17–39%. At 24 but not 48 weeks, simple hyperplasia was observed in one subject in each of the less than monthly progestin groups. Significant increases (P<.05) of high-density lipoprotein cholesterol were observed before but not after medroxyprogesterone acetate in the women receiving it less than monthly. No change was seen with monthly progestin.
Conclusions: In this direct comparison, medroxyprogesterone acetate given for 14 days every 3 months elicited less vaginal bleeding than standard monthly administration. Only a single woman had simple hyperplasia with each regimen of progestin given every 84 days. Medroxyprogesterone acetate given for 14 days every 3 months represents a possible alternative to standard monthly therapy if coupled with regular assessment of the endometrium.
© 1994 The American College of Obstetricians and Gynecologists