Trial to Compare the Effects of Tibolone (Livial®) and Continuous Combined Low-Dose Estradiol/Noresterone (Activelle®)

Inclusion Criteria: * Subjects must be healthy and postmenopausal women, \>= 45 and \< 65 years of age, with an intact uterus. * Subjects must have been postmenopausal for less than 15 years. * Body Mass Index \>18 and =\< 32 kg/m2. * Voluntary written informed consent is required. Exclusion Criteria: * Any unexplained abnormal uterine bleeding after the menopause. * Double layer endometrial thickness = 6 mm as assessed by transvaginal ultrasonography. * Treatment with oral estrogen and/or progestogen therapy within 4 weeks prior to screening, or treatment with transdermal therapy and local estrogen applications within 4 weeks prior to screening. * Any previous or current unopposed estrogen administration, prior use of estrogen pellets or tamoxifen citrate (occasional use of estrogen-containing vaginal cream is allowed after the appropriate wash-out period is completed). Estrogen combined with sequential administration of progestogen should have been at least 10 days per 28 day cycle. * The following wash-out periods apply: * 4 weeks for transdermal hormonal treatment, local estrogen applications or other non-hormonal medication known to act on the relief of vasomotor symptoms (e.g. clonidine) * 4 weeks for phytoestrogens, tibolone, intra-uterine or oral progestogen and oral estrogen/progestogen therapy * 6 months for progestogen implants or injections and estrogen/progestogen injectable therapy. * Any subjects who are either using phytoestrogens, tibolone, intra-ut…