In the United States, the average age of women when they enter menopause is 51. Perimenopause includes the transition from having regular menstrual cycles to the complete cessation of menstrual cycles. It usually begins when a woman who previously had regular menstrual cycles with a predictable length begins having irregular periods before eventually having no periods at all. Women enter perimenopause on average about 4 years before they stop having periods altogether (age 47.5). Some women begin to have symptoms such as hot flashes, even while they are still having regular periods. Menopause and perimenopause are normal transitions in a woman’s life, but they often cause symptoms that are very bothersome.