At least for me, the stigma about a mother having children later in life, such as 40 years old or older, is pretty firmly established. As women, we all hear about the problems that could come from having a child too late, such as Down’s syndrome and a horrifying range of genetic defects. In the meantime, men have appeared to be immune from this. Most people seem to believe that a man’s sperm is just as good at 81 as it was at 21. At least in the case of daughters though, this might not be true.

First of all, everyone understands the pressures of modern society and how they tend to push back childbirth. In fact, from a financial standpoint, it’s definitely smart to delay having children. Unfortunately, biology hasn’t caught up with our curious modern ways and modern technology, so even though it’s now entirely possible to conceive at older ages, it’s not necessarily a wise decision. Here’s why.

Just as older women can cause deleterious effects in their children, so can men. Spontaneous mutation of cells is a lot higher in male sperm cells than female ovaries, and this rate increases dramatically with paternal age. The results of a complex study of extinct cohorts from 1800 through 1899 showed that daughters born to older fathers (from about 45 to 55 years of age) lived shorter lives. Not only that, but it got worse the older the father was: approximately a half-year shorter for the daughter per year older for the father.

As awful as this is, it does bring up one interesting point. This study showed this pattern consistently in daughters but saw little to no effect in sons. The reason is that the lifespan shortening effect seems to occur in the paternal X-chromosome, and as we all learned in high school biology, boys inherit a Y-chromosome from their fathers. Of course, hope is not lost for daughters born to older fathers. There’s a mutation theory of lifespan that focuses on the mutation rate of somatic cells. If the father’s mutation rate is still relatively low, their offspring are able to have normal lifespans.

One more fascinating tidbit is that daughters born to very young fathers (from 25 years of age and younger) actually live shorter lives as well. While it’s probably not practical to live our lives by focusing too heavily on the results of these studies, it’s worth bearing in mind.

Gavrilov, L. A. (2001). Human Longevity and Parental Age at Conception. Springer Link. Retrieved May 17, 2013.