If you are asking this question, then you are most likely between 45-50 years of age and you have noticed some changes in your menstrual cycle pattern and emotions. The medical definition of menopause is the cessation of menstrual periods and therefore, can only be diagnosed in retrospect.
A general rule of thumb is that if you are over 45 years of age and have not had a period for 12 months, they are probably finished. Most Australian women reach menopause between the age of 45-55 years, with the average age being 51 years. However, there is considerable variation and some women may reach menopause in their early 40?s, whilst others will continue to menstruate until their late 50?s.
A long term study of Australian women called The Melbourne Womens Midlife Health Study, tracked over 400 women through this phase. They found that if you have had at least 3 months without menstruating, then your last period will probably come within