Menopause occurs naturally when a woman's ovaries run out of functioning eggs. At the time of birth, most females have about 1 to 3 million eggs, which are gradually lost throughout a woman's life. By the time of a girl's first menstrual period, she has an average of about 400,000 eggs. By the time of menopause, a woman may have fewer than 10,000 eggs. A small percentage of these eggs are lost through normal ovulation (the monthly cycle). Most eggs die off through a process called atresia.
Normally, FSH, or follicle-stimulating hormone (a reproductive hormone), is the substance responsible for the growth of ovarian follicles (eggs) during the first half of a woman's menstrual cycle. As menopause approaches, the remaining eggs become more resistant to FSH, and the ovaries dramatically reduce their production of a hormone called estrogen.
Estrogen affects many parts of the body, including the blood vessels, heart, bone, breasts, uterus, urinary system, skin, and brain. Loss of estrogen is believed to be the cause of many of the symptoms associated with menopause. At the time of menopause, the ovaries also decrease their production of testosterone -- a hormone involved with sex drive.
When she was 26, Lara Dietz learned she had breast cancer -- a shock to this mother of two very young children. Then came the second blow. When treatment began, so did premature menopause. "I was having hot flashes," she says. "I felt like I was 55 years old."
When menopause occurs between ages 45 to 55, it is considered "natural." When it occurs before age 40 -- regardless the cause -- it is called premature menopause. The ovaries no longer produce an egg each month, so monthly menstrual cycles...