Menopause is a natural and normal part of every woman's life.  Some women find the period and process frustrating, while others find it liberating.  For all, it is a time of change. 

What is menopause?
Menopause describes the time after a woman's last menstrual cycle when her period of fertility ends.  During this time, a woman's ovaries no longer produce estrogen (three types of estrogen include estradiol, estron and estriol) and progesterone.   Menopause usually occurs between the ages of 40 to 55; the average age for menopausal women is 51.  

The stages of menopause
Before a woman's final menstrual period, she will experience changes in her cycle.  This period is called the menopausal transition and although not technically menopause, the transition time is characterized by symptoms that are similar to menopause.   To better understand menopause, let's look at the stages of menopause:

Pre - menopause
This is the normal, reproductive time of a woman's life which starts with a woman's first period, and ends with her last regular menstrual period. Note: some doctors use the terms pre-menopause and perimenopause interchangeably, and so refer to this phase as a time of a few years, from the beginning of early menopausal symptoms until the end of menstrual bleeding. 

Peri - menopause
This is the time in which hormone levels fluctuate, thus causing symptoms such as 'hot flashes.'  Perimenopause occurs 2 to 10 years before complete cessation of the menstrual period.  While this is a transition period to menopause, a woman may still get pregnant as long as she is getting her periods (even though they may not be regular).  Women experience perimenopause for different amounts of time, and cannot know in advance how long it will take to reach menopause. 

Menopause
This is the time in a woman's life in which the ovaries no longer produce eggs, and a woman is no longer able to get pregnant naturally.  Estrogen and progesterone levels drop permanently and significantly.  Symptoms of perimenopause and menopause are almost the same, with the most significant difference being the end of the menstrual cycle. 

Post-menopause
This is defined as 12 months after the last menstrual cycle, or menstrual period.  This stage continues during the rest of a woman's life.   

Premature menopause
Menopause can occur at earlier stages of a woman's life (before the age of 40), a condition that is called "premature menopause".  Premature menopause can be due to chemotherapy or radiation treatment for cancer (e.g. pelvic cancer), autoimmune diseases that attack the ovaries, genetic defects, or be caused by surgical removal of the ovaries.  During all of these situations, a more rapid  or even immediate reduction of estrogen and progesterone occurs, thus causing more intense menopausal symptoms. 

The life transition times of perimenopause and menopause are characterized by many symptoms, and can be a source of frustration for many women.  How can you know if you're experiencing symptoms of menopause?  Read our next section about Menopause Symptoms to learn more.