For most women, the menopause – when menstruation ceases permanently – occurs at around the age of 51. Periods will stop suddenly for one in ten women, but the vast majority – about 80 per cent – experience symptoms in the run up to menopause.1,2

This perimenopausal phase is also known as menstrual transition (MT) or the climacteric. It lasts four years for about half of women but symptoms can continue longer than a decade for one in ten. The most commonly experienced effects are heavy and/or irregular periods, vasomotor effects of hot flushes and night sweats, and breast tenderness.2,3

About 5 per cent of women experience natural menopause by the age of 45, and is described as ‘premature menopause’ when it happens before the age of 40. Also known as ‘premature ovarian insufficiency’ (POI) or ‘premature ovarian failure’, premature menopause occurs at the rate of about one in every 100 women under the age of 40, one in 1,000 women under 30 and one in 10,000 under 20.1,4

The term ‘post-menopause’ is used to describe the time once a woman has not had a period (amenorrhoea) for 12 consecutive months.1