Menopause starts as the functioning of the ovaries begin to change. The ripening and release of the ovum (which, during the reproductive years leads to ovulation and then menstruation if pregnancy does not occur), becomes unpredictable. Ovulations start to be skipped, and the menstrual cycle starts to become less reliable in timing. As these changes become more pronounced, periods start to be skipped, and other perimenopausal symptoms may appear.
After a number of years of erratic functioning, the ovaries almost completely stop producing progesterone and two out of the three estrogen hormones: estradiol and estriol. Estrone is one estrogen which is still produced in reasonable amounts in post-menopausal women. Testosterone levels decrease; however, a decrease in testosterone levels begins gradually in young adulthood. Testosterone levels are thought not to drop significantly during the menopause transition because the stroma of the postmenopausal ovary and the adrenal gland still continue to secrete small amounts of testosterone, even during post-menopause.
Menopause is the end of the reproductive years rather than the beginning, and thus it is the opposite of menarche, nonetheless it can usefully be compared with that event: the menopause transition years are in many ways similar to puberty in that women experience hormonal fluctuations which usher in a new stage of life. Similar to pubescent girls, menopausal women are often unfamiliar or uneducated about the types of bodily changes they are undergoing, and may require a period of adjustment to the accompanying effects of these changes.
The above information thankfully comes from the Mayo Clinic.com at the following link.
