Approximately 20 percent of embryos from the very young patients will be seen as a fetal sac 4 weeks after embryo transfer, while as low as 3 to 5 percent of embryos produced by women older than age 42 will implant, many of them miscarrying. Initially, there was speculation as to the relative contribution of the uterus and the ovary to this phenomenon, but since the advent of the donor egg, it seems mostly an egg ageing situation. Research on embryos has shown that abnormalities greatly increase as women age. It seems that men also undergo reproductive ageing but at a slower rate than women and offset by a decade or two. Certainly there is no obvious end to reproduction for men comparable to menopause in women, but sperm counts in older men do diminish.
Information suggests that the risk of genetic abnormalities from older men is greater, as well.
In fact, cell ageing is a subject of great interest among scientists. Ageing is all in our genes. The key is a thing called telomere, a tiny bit of ilfe's software at the tip of every chromosome. It is a biological clock, ticking inside each of your cells and telling them when to call it quits. The telomere, containing bits of DNA, is shortened each time a cell divides.