At menopause, a woman's ovaries permanently decrease their production of the hormones estrogen and progesterone, leading to the end of menstruation. In the years around menopause, the changes in hormone levels result in symptoms including hot flashes, night sweats, mood swings, and vaginal dryness. The lower hormone levels also put women at risk for osteoporosis and heart disease. Postmenopausal hormone replacement therapy (HRT) refers to regimens of the female hormone estrogen with or without progesterone. This therapy reduces the uncomfortable symptoms of menopause. It also influences the development (favorably and unfavorably) of conditions such as thinning of the bones, heart disease, stroke, blood clots, dementia, and some cancers. Before the July 2002 publication of the results of a large, high-quality study called the Women's Health Initiative (WHI), research suggested that the benefits of combination HRT (estrogen and progesterone) outweighed the risks. However, the WHI study showed that women receiving HRT actually had a higher risk of heart disease and stroke than did women not receiving HRT. The results of the WHI study received a lot of media attention. However, there is often a delay before patients and doctors change practice after study results become available.