Perimenopause

You are born with a set number of follicles (eggs) in your ovary and over the years this 'store of eggs' slowly declines. Most of your estrogen, your progesterone and some of your testosterone is made in these follicles. As the number of follicles slowly declines the production of estradiol, progesterone and testosterone is declining. The hormone levels fluctuate and become imbalanced, causing irregular cycles and many different symptoms. As this is a gradual process, many women start having symptoms and/or period changes years before the actual menopause and this phase is called the perimenopause and often starts in a woman's 40's or earlier.