The menopause transition, also known as perimenopause, is the period leading up to menopause when a woman's body undergoes hormonal changes. This phase typically begins in a woman's 40s but can start earlier or later. During this time, estrogen and progesterone levels fluctuate, leading to various physical and emotional symptoms. Common symptoms of the menopause transition include irregular periods, hot flashes, night sweats, mood swings, and sleep disturbances. This transition can last several years, and eventually, a woman will reach menopause, defined as having no menstrual periods for 12 consecutive months.