For decades, women have been warned about their ticking biological clocks, the metaphor used to describe the limited years during which a woman can successfully become pregnant. Men, on the other hand, have lived under the illusion that they are blessed with lifelong fertility and can father a child well into their golden years.

But new research indicates that sperm may lose something as a male ages, and that something might just affect a man's progeny. Studies have found that as men grow older, the number of genetic mutations in their sperm increases significantly — increasing their potential children's risk for mental disorders, particularly autism.  

One such study, the Malaysian Mental Health Survey, found that children with older fathers were at increased risk for anxiety, depression, obsessive-compulsive disorder and phobias. The prevalence of mental disorders in kids whose fathers were 19 or younger when their child was born was just nine percent. For children whose fathers were 50 and older when their baby was born, that rate jumped to 42 percent.  

These results were confirmed by another study linking mental disorders in children to increased paternal age. In a study conducted at the Karolinska Institute in Stockholm, Sweden, researchers found that men between the ages of 40 and 49 were 1.4 times more likely to have children with a diagnosis of autism than 15- to 29-year-old men. Men who became fathers between the ages of 50 and 54 were 2.2 times more likely to have children with a diagnosis of autism. And for men aged 55 and above, the risk jumped to 4.4 times more likely.

So while a man might still be capable of fathering a child, the risks to his unborn children increase with every paternal year. That biological clock is ticking just as loudly for men as it has always been for women. Talk to your health care provider about individual risks if you're concerned.

Kids of older dads have greater risk of mental illness
New research finds that biological clocks are ticking for men too.