When we talk about aging and fertility, we're usually talking about women. There is plenty of research on ovarian reserves. But in recent years, researchers have begun to pay more attention to what happens to semen and sperm as a man's birthdays go by.
While there isn't a wealth of information yet, we do know that the sperm of older men is linked to genetic problems such as Lesch Nyhan Syndrome, polycystic kidney disease and Hemophilia A [source: Herbert]. Advanced age in a father has also been linked to autism, Down syndrome, epilepsy and schizophrenia [source: Donnelly]. Men are still producing sperm in their 70s, but it isn't the same quality.
That isn't to say that older men shouldn't father children. Rather, the more we know about how aging affects both men and women, the better we can work toward the best outcomes for their kids.