Menopause comes next, the end of your menstrual periods. After a full year without a period, you can say you have been “through menopause,” and perimenopause is over. Postmenopause follows perimenopause and lasts the rest of your life. The average age of a woman having her last period, menopause, is 51. But, some women have their last period in their forties, and some have it later in their fifties. Smoking can lead to early menopause. So can some types of operations.