Postmenopausal women who have had a hysterectomy should not take estrogen replacement therapy (ERT) to prevent osteoporosis, stroke, or heart disease, according to new guidelines from the US Preventive Services Task Force. The recommendation was based on evidence from the ongoing Women's Health Initiative clinical trial, along with other studies. Although estrogen has positive effects, regular use of ERT may increase the risk of potentially fatal blood clots, stroke, dementia, and mild cognitive impairment. The task force stated that any benefits of ERT are outweighed by these harmful effects. The group encourages women to discuss other options for preventing bone fractures, cancer, or heart disease with their doctors.