Some say ' Premenopause ' refers to the years when your menstrual cycle is regular. This can only be accomplished by looking back over your menstrual cycle for the last 12 months. In other words it is impossible for a woman to know exact moment that she is experiencing menopause. As, you can see these terms can be very very confusing.
Symptoms are the major factor.
In figure 1, the stages are for women who experience menopause naturally. These are average age stages, however woman can experience premature or late menopause. Premature as early as age 35, and late menopause occurring after the age of 55. Talk to your health care provider about your symptoms not your age. Unlike the gradual changes that are experienced during natural menopause, women often have sudden and abrupt drop in hormones and symptoms may be dramatic, both physically and psychologically.