Menopause is the time that marks the end of a womans menstrual cycles. It is diagnosed after a woman has gone 12 consecutive months without a menstrual period. Menopause can happen in a womans 40s or 50s, but the average age is 51 in the United States. However, it can also happen before the age of 40, which is called premature menopause.

Before menopause, a woman may experience perimenopause, which is the transition to menopause that can last between two and eight years. During perimenopause, a womans menstrual periods may become longer or shorter, heavier or lighter, and more or less frequent, until eventually, on average, by age 51, her ovaries stop releasing eggs, and she has no more periods. Most likely, a woman will experience some irregularity in her periods before they end. Skipping periods during perimenopause is common and expected. Often, menstrual periods will skip a month and return, or skip several months and then start monthly cycles again for a few months. Periods also tend to happen on shorter cycles, so they are closer together. Despite irregular periods, pregnancy is possible.

In summary, menopause is diagnosed after a woman has gone 12 consecutive months without a menstrual period, and it can happen in a womans 40s or 50s, but the average age is 51 in the United States. Before menopause, a woman may experience perimenopause, which is the transition to menopause that can last between two and eight years.