What were the findings of the Women's Health Initiative Observational Study regarding oophorectomy vs ovarian conservation with hysterectomy? 
In the Women's Health Initiative Observational Study, oophorectomy was found to be associated with an increased risk of cardiovascular disease, hip fracture, and cancer compared to ovarian conservation with hysterectomy. Additionally, hormone therapy was found to reduce the risk of disease and prolong life in postmenopausal women. 