Bleeding patterns in postmenopausal women using continuous combination hormone replacement therapy with conjugated estrogen and medroxyprogesterone acetate or with 17β-estradiol and norethindrone acetate

Objective: We studied bleeding patterns in postmenopausal women who were using 2 types of continuous combination regimens. Study Design: A prospective, double-blind, randomized study of 208 postmenopausal women treated with conjugated estrogen, 0.625 mg, and medroxyprogesterone acetate, 5 mg, or with 17β-estradiol, 2 mg, and norethindrone acetate, 1 mg. Results: The mean number of bleeding days decreased during the first 4 months of treatment (P< .002) but not thereafter. The number of bleeding days was fewer (P< .002) and the time until amenorrhea was shorter (P< .02) in patients receiving conjugated estrogen and medroxyprogesterone acetate than in patients receiving 17β-estradiol and norethindrone acetate. The odds ratio for progression to amenorrhea with the use of conjugated estrogen and medroxyprogesterone acetate was 1.58, in comparison with the use of 17β-estradiol and norethindrone acetate. A thick endometrium at the start of treatment resulted in more bleeding days than were found for a thin endometrium (P< .03). Body mass index, age, and blood pressure had no predictive value for bleeding problems. Conclusions: Treatment with continuous combined conjugated estrogen and medroxyprogesterone acetate resulted in fewer bleeding problems than did treatment with 17β-estradiol and norethindrone acetate. Endometrial thickness may help to predict the chance of achieving amenorrhea during early hormone replacement therapy. (Am J Obstet Gynecol 2001;184:1131-8.)