In 1994, researchers at the US National Institutes of Health, or NIH, started the Study of Women’s Health Across the Nation, or SWAN, to examine the bodily changes that occur in US women during middle age. Many of those changes are a result of menopause, which is the time twelve months after a female has had their last menstrual period. In the late 1990s, menopause was under-researched, and studies that did exist were based on participants who were not representative of the whole US population. SWAN investigators pushed for the inclusion of various racial and ethnic groups in their study to gain a broader understanding of menopause and aging. In particular, the researchers aimed to explore how symptoms of menopause differ among women, how those symptoms change over time, and how they can lead to certain health risks later in life. SWAN was among the first long-term studies to use a large, racially and ethnically diverse group of participants to study women’s transition into menopause and how it differs from chronological aging.