EurekAlert! -- Eighteen years ago this month the National Institutes of Health (NIH) announced that it would sponsor a landmark study to examine women and cardiovascular disease. Known as the Women’s Health Initiative (WHI), the study enrolled more than 161,000 women. By 2004 however, the government had ended two arms of the study involving estrogen after researchers found it posed a small but detrimental risk for stroke to postmenopausal women taking the hormone. The findings caught many members of the scientific community by surprise as estrogen had previously been shown to protect the brain from stroke in animal models.