A woman’s reproductive potential is very much influenced affected by her “biological clock” which comprises two components:
1. Age: Advancing age is inevitably accompanied by a progressive reduction in the number of eggs in the ovaries (“ovarian reserve”). As a diminution in ovarian reserve (DOR) ultimately passes a theoretical “threshold” the woman becomes progressively more resistant to stimulation with fertility drugs. This is accompanied by a fall in blood AMH levels and a rise in basal blood FSH. After several years of progressive DOR, the ovarian reserve is ultimately depleted, and ovulation as well as cyclical menstruation ceases (menopause).
2. “Egg Competency” The second component of the biological clock is an inevitable age-related decline in egg competency (the ability of an egg, upon fertilization, to propagate a healthy embryo) . The most important manifestation of this age-related occurrence is an inevitable and rapid increase in the percentage of eggs that have numerical chromosome irregularities (aneuploidy). By way of example, at age 30Y, about one out of every two human eggs will be aneuploid while at 45Y more than nine out of ten are so afflicted. Aneuploid eggs cannot propagate healthy babies. Most will not even fertilize and those that do, will usually be lost as early miscarriages or go on to produce a birth defect such as Down syndrome.
It is important to understand is that e the two components of the biological clock (i.e. ovarian reserve and age) represent variables which while they are often interrelated and inter-dependent can often exist independently. By way of example, some older women in their mid-forties have excellent ovarian reserve while some young women in their thirties have DOR. Yet while they produce fewer eggs, the potential competency of the eggs they produce is largely tied to their age. However, the ovarian hormonal environment brought about by DOR and the protocol used for ovarian stimulation, is readily affected by the protocol used for ovarian stimulation. Selection of the wrong stimulation protocol can adversely influence egg competency. Conversely, an individualized and optimal protocol for ovarian stimulation by favorably regulating the ovarian hormonal environment, can improve the potential for optimal follicle and egg development thereby minimizing the risk of egg aneuploidy. The problem is that it becomes progressively more difficult to optimally regulate the intra-ovarian hormonal environment in older women, and in those with DOR, and it is here that the use of human growth hormone can play a valuable role.
Several researchers have shown that the administration of human growth hormone (HGH), as an adjunct to ovarian stimulation, enhances follicle response in older women and those with DOR and so can help optimize egg quality. It is thought that HGH hormone by increasing the production of insulin-like growth factor 1 (IGF-1), improves follicle development, estrogen hormone production and egg maturation. Two basic mechanisms have been proposed: 1) improving the response to gonadotropin therapy by up-regulating the FSH receptors on the granulosa cells that form the inner lining of follicles and, 2) through a direct enhancing effect of HGH on the egg’s mitochondrial activity. While human eggs do have HGH receptors, those retrieved from older women show decreased expression of such receptors (as well as a reduction in the number of functional mitochondria) as compared with those derived from younger women. In fact, it has recently been shown that older women treated with HGH showed a marked increase in functional mitochondria in their eggs along with improved egg quality.
My own experience in selectively prescribing HGH as an adjuvant to women with DOR, older women and those with unexplained egg quality deficits, is that if used in combination with individualized protocols of ovarian stimulation it does indeed enhance egg quality and ovarian response, culminating in improved IVF outcome.
I hope this helps!