Getting your first period may have been a surprise. But menopause—when your estrogen levels drop and your period stops permanently—is very different. Its onset is usually gradual, marked by a series of hormonal changes in your body that often cause noticeable symptoms. This can last anywhere from a year to almost 10 years.

Perimenopause, when the ovaries begin to slow estrogen production, tends to start in your 40s. And the average age of reaching menopause is 51, according to The American College of Obstetricians and Gynecologists.

While some symptoms are common, the menopausal experience is unique for every woman.