The terms describing a woman’s transition from having regular periods to none at all can be confusing. You will often see the terms ‘premenopausal,’ ‘menopausal,’ and ‘postmenopausal’ used to denote, respectively, the years before any menstrual irregularities occur, the time when periods have recently stopped for good, and the years after this transition and through the rest of a woman’s life. Alternatively, the term ‘the climacteric’ is used to denote the period when the change in menstruation occurs.
The confusion arises when one looks at the technical definition of menopause: it is the cessation of menses for 12 months. But this is a discrete event that begins and ends on the last day of the twelfth month after a woman’s last period. Is a woman postmenopausal on the next day and is she premenopausal the day before? Recent studies have demonstrated that the process of reproductive aging in a woman is more continuous—as are all aging processes—and therefore we prefer a different terminology.
In order to understand what happens to a woman’s reproductive system as she grows older, it is necessary to review the normal menstrual cycle. The purpose of the menstrual cycle is to prepare the lining of the uterus for implantation of a fertilized egg, the beginning of pregnancy. To accomplish this, the pituitary gland starts to release follicle stimulating hormone (FSH) to stimulate the ovaries to start producing estradiol (the principal estrogen of the menstrual cycle). FSH also recruits one of the remaining immature eggs (called follicles) to mature and become the one that will be ovulated. Estradiol stimulates the cells lining the uterus to proliferate and cause thickening of the uterine wall. In a normal menstrual cycle, this stimulation continues for the next 14 days. Then the increased level of estradiol causes a surge in the pituitary hormone call luteinizing hormone (LH) which causes the release of an egg from an ovary--ovulation. The egg travels down the fallopian tube to the uterine cavity in anticipation of being fertilized. Meanwhile, the part of the ovary from which the egg left (the corpus luteum) starts to produce progesterone which stabilizes the lining of the uterus and readies it for implantation after fertilization. If it is not fertilized, it does not implant. The corpus luteum stops producing progesterone after about two weeks and without this support, the lining of the uterus sheds. Thus, the cycle ends and the period starts a new cycle.
This normal cycle, however, does not continue unchanged from the first period to the last in a woman’s life. There are a number of stages:
After menarche, the age at which an adolescent has her first period, there is a time of menstrual irregularities and less than optimal fertility. Over the next few years, her ovulation regularizes and in her late teens and through her twenties a woman has her greatest fertility.
As she enters her thirties, and especially after her mid thirties, a woman’s reproductive capacity (her ability to get pregnant and subsequently deliver) starts to decline. She may decrease her production of estrogen slightly on average, and her progesterone production in the second half of the cycle can decrease. During this time, however, she usually continues to ovulate and her menstrual cycle generally remains regular and normal, even though her reproductive capacity has decreased.
Over the next five to ten years, a woman's menstrual cycle can become very disrupted and estrogen levels can swing from very high (above the normal when she was young) to very low (virtually no estrogen as in the menopause ). This can result is alternating sensations of enlarged and tender breasts with bloating and irritability when estrogen is dominant; and hot flushes, confused thinking or lack of concentration, memory difficulties and vaginal dryness when the estrogen level plummets. Accompanying these swings can be cycles in which no ovulation occurs and therefore no progesterone is produced to counteract the effects of the estrogen and to regularize your periods. This leads to times when there is no bleeding (often leading to the worry that a pregnancy has occurred or menopause has started), which can then be followed by heavy bleeding (dysfunctional uterine bleeding) accompanied by severe cramps (dysmenorrhea). In the past few years, the term ‘perimenopause’ has been adopted to denote these symptoms that occur in the 5 to 10 years prior to menopause.
The menopause, as defined above, can only be defined retrospectively, i.e., after a woman has gone twelve months without having a period. At this point, estrogen levels have remained so low that the lining of the uterus is not stimulated to build up enough to shed and therefore periods no longer occur. This continued low level of estrogen is reflected in the lack of fluctuation between heavy bleeding and breast tenderness, and no periods and shrinking breasts. These continued low levels can cause an increase in hot flushes ( most women start to experience hot flushes in the perimenopause), difficulty concentrating, and memory problems. The loss of bone accelerates at this point and in the first five years after menopause a woman loses bone at a faster rate than at any time in her life. Other symptoms of the perimenopause may intensify, such as vaginal dryness, decreased libido, dry skin, and decreased mood and energy.
Five years after the menopause, a period often referred to as the 'post menopause,' a woman's body settles into a lower estrogen state, bone loss slows down--but definitely continues--and many women become acclimated to the symptoms. Unfortunately, the damage to the many organ systems that need estrogen continues insidiously. Consequently, cardiovascular disease rates increase; osteoporosis and fracture rates increase; diabetes rates increase; Alzheimer's disease rates increase.
So as you can see, the 'pause' in 'menopause' refers only to a discreet point with regard to menstrual periods; the aging of a woman's reproductive system is actually a fairly continuous process that starts in the early thirties. An anti-aging medicine approach takes this into account and intervenes before the actual menopause to treat the symptoms and long term consequences that result from less than optimal hormone levels.
When does an anti-aging approach to reproductive aging start? Which among the various options for hormone replacement does it employ? These questions will be addressed in the following sections.
NEXT: What is Estrogen?