It is generally believed by most clinicians that the postmenopausal phase begins when 12 full months have passed since the last menstrual period. A rising FSH level indicates to the clinician that the pituitary is working overtime in a futile effort to stimulate the ovaries to produce eggs which no longer exist. Most researchers use a 35-50 FSH level as the gauge whether a woman has reached postmenopause. This high FSH level continues for the rest of a woman's life unless HRT is started, but this continuing high level is not harmful. Another major change that occurs after menopause is that estrogen production shifts from the ovaries to the fat cells in a woman's body.
Some estrogen continues to be produced by the adrenals but in a lesser amount.
Hopefully, by the time a woman reaches postmenopause, she will have practiced good health habits throughout her life and, consequently, approaches this time of life well-prepared both physiologically and emotionally. Ideally, the menopausal woman will have built up bone mass during her younger years, so that if bone loss now occurs it won't be as devastating as it might be if she has been very casual about good health measures. The healthy woman passes through menopause with fewer problems than one who has not prepared herself. There is more time now for women to take care of themselves. Childbearing and childrearing years are past, and most women are no longer faced with major career decisions.