The menopause quite literally means "stopping of the periods" and is nature's way of finishing a woman's reproductive ability before moving on to the next stage of her life. Unfortunately the method of terminating fertility involves the ovaries stopping all their functions, not just the ability to present eggs each month for fertilising.
As a result the ovaries no longer produce the hormones oestrogen and progesterone and this leads to various symptoms associated with the menopausal process.
The average woman passes through the menopause at the age of 51 years, although the normal range is 46 - 56 years. The process can be gradual or sudden, taking many years or just happening overnight. Occasionally it can occur at a much younger age - even in the twenties.
An artificial menopause can be created following surgery - a hysterectomy with conservation of the ovaries can bring it on several years early and, of course, removal of the ovaries themselves will produce an "instant" menopause. A hysterectomy results in cessation of the periods but the hormones are still produced until the ovaries eventually fail.