Women's Health Initiative (WHI) Study

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The 2002 Women's Health Initiative (WHI) study was conducted to investigate the effects of hormone replacement therapy (HRT) on women's health. The study focused on two substances, conjugated equine estrogens (CEE) and medroxyprogesterone acetate (MPA). The findings revealed that the combined use of estrogen and progestin (E + P) increased the risks of cardiovascular disease, breast cancer, deep vein thrombosis, and Alzheimer's disease in women. However, the use of CEE alone did not exhibit the same risks. As a result of these findings, there was a significant change in how physicians prescribed HRT, leading to a substantial decline in HRT prescriptions. The study's outcomes have created confusion and misconceptions surrounding estrogen supplementation and have also influenced perceptions regarding the use of testosterone in women.


The study was initiated by the National Heart, Lung, and Blood Institute (NHLBI) of the United States National Institutes of Health (NIH) in 1991.