Menopause is the stage in a woman’s life when her monthly periods stop. It is the end of a woman’s reproductive years. Perimenopause is the first stage of this process and can begin eight to 10 years before menopause. Menopause is the point when a woman has not had a menstrual period for at least 12 months. Postmenopause is the stage after menopause. Menopause is the end of a woman’s menstrual cycle and fertility. This happens when: Your ovaries no longer make estrogen and progesterone, two hormones necessary for reproduction and Your periods have stopped for 1 year. Menopause naturally occurs with age. But it can also be due to surgery, treatment of some disease or due to some disease. In these cases it may be called induced menopause, surgical menopause, or primary ovarian insufficiency, depending on the cause. Menopause begins around age 51 when it occurs naturally. But it could happen before you turn 40. This is called premature menopause. The age at which you start is mostly determined by your genes.