Vaginal rings delivering progesterone and estradiol may be a new method of hormone replacement therapy.

OBJECTIVE To determine whether a low dose of P delivered together with E(2) from a vaginal ring on a continuous schedule can prevent endometrial proliferation and yield a bleeding pattern dominated by amenorrhea. DESIGN Longitudinal clinical study. SETTING Three university hospitals. PATIENT(S) Fifty-five women 45 to 75 years of age, not hysterectomized, with E(2) levels of <20 pg/mL and hot-flash incidence of two or more per day in the past week. INTERVENTION(S) A vaginal ring delivering approximately 150 microg/d of 17beta-E(2) and approximately 5 mg/d or approximately 9 mg/d of P used continuously for 4 and 6 months. MAIN OUTCOME MEASURE(S) Endometrial thickness, bleeding pattern, and hot flash incidence. RESULT(S) Endometrial proliferation was prevented by both P doses. Bleeding incidence decreased. In months 4, 5, and 6, 8 of 12 women had no bleeding. Incidence of hot flashes and night sweats decreased quickly and significantly. CONCLUSION(S) A vaginal ring delivering E(2) and a low dose of P merits further study as a method for long-term hormone replacement therapy.