- Arm I: Patients receive one of the following: Women with an intact uterus whose last menstrual bleeding has occurred within 2 years receive continuous oral cyclic estradiol-norethindrone combination comprising estradiol only on days 1-12, estradiol plus norethindrone on days 13-22, and then estradiol only on days 22-28. Women with an intact uterus whose last menstrual bleeding occurred more than 2 years prior to study receive continuous daily oral estradiol-norethindrone combination. Women who have had a hysterectomy receive continuous daily oral estradiol only.