Perimenopause is the time in a woman's life when physiological changes occur that begin the transition to menopause. Menopause is the time when there have been no menstrual periods for 12 consecutive months. A woman can usually tell if she is experiencing symptoms characteristic of perimenopause because her menstrual periods start changing.
The changes in the menopause transition (perimenopause) typically begin several years before the natural menopause. This is a time when the levels of hormones produced by the aging ovaries fluctuate, leading to irregular menstrual patterns (irregularity in the length of the period, the time between periods, and the level of flow) and hot flashes (a sudden warm feeling with blushing). Other changes associated with perimenopause and menopause include night sweats, mood swings, vaginal dryness, fluctuations in sexual desire (libido), forgetfulness, trouble sleeping, and fatigue (probably from the loss of sleep).
The timing of natural menopause is variable. In the western world, the average age of menopause is now 51. There is no relation between the time of a woman's first period and her age at menopause. The age at menopause is not influenced by a woman's race, height, number of children, or use of oral contraceptives.