Menopause is a point in time 12 months after a womans last period. The years leading up to that point, when women may have changes in their monthly cycles, hot flashes, or other symptoms, are called the menopausal transition or perimenopause. The menopausal transition most often begins between ages 45 and 55, but it can start as early as the mid-30s or as late as the early 60s. It usually lasts about seven years but can be as long as 14 years. The duration can depend on lifestyle factors such as smoking, age it begins, and race and ethnicity. Genetics also seem to play a strong role in determining the age at which a woman will reach menopause.

In rare cases, menopause can happen before age 40, which is called premature menopause. Premature menopause may result from the failure of the ovaries to produce normal levels of reproductive hormones, which can stem from genetic factors or autoimmune disease. For these women, hormone therapy is typically recommended at least until the natural age of menopause to protect the brain, heart, and bones.

In summary, the age at which a woman starts menopause can vary widely, but the menopausal transition most often begins between ages 45 and 55.