"The optimal time for a man to father a healthy child is the same as for a woman — 25 or so," says Dolores Malaspina,

Sunday, October 15, 2006 - Page updated at 12:00 AM



Carnal Knowledge

Like eggs, sperm have a "best by" date
By Faye Flam

The Philadelphia Inquirer

By the time I'd reached my early 30s and was still not married, someone offered me this bit of advice: Just pick somebody.

Women are relentlessly reminded of the dreaded biological clock and the risks of having children after 35. But recent science suggests men, too, should be worried.

"The term 'biological clock' has always referred to females, but now there's evidence men are also ticking off some of their healthy children," says Jay Schinfeld, a fertility specialist.

The latest finding, published last month: Older fathers are more likely to have children with autism. Researchers tracked 387,000 people born in Israel and concluded the odds of fathering an autistic child are about 6 in 1,000 for men under 20. When a man reaches 50, those odds shoot up to about 52 in 1,000.

"The optimal time for a man to father a healthy child is the same as for a woman — 25 or so," says Dolores Malaspina, a psychiatry professor at New York University and coauthor of the study.

Malaspina led an earlier study showing a connection between paternal age and schizophrenia. She found children born to fathers over 50 carried about three times the risk of developing schizophrenia as those born to fathers in their 20s.

Autism and schizophrenia both arise from a little-understood combination of genetic and environmental triggers. Both disorders tend to run in families, suggesting that genetic risk factors can be inherited.

But you don't have to carry a genetic disease to pass one on — the trouble can start in your testicles. There, sperm-generating cells divide about 23 times a year, in the process slowly accumulating copying errors.

Older fathers are more likely to have children with achondroplasia (dwarfism) and several other conditions caused by spelling errors in the DNA. So for a man, the older you get, the less your child's genetic endowment will resemble your own.

For women, aging isn't as likely to lead to spelling errors because we make no new eggs after we're born. But that leads to other problems. The million or so we begin life with die at a rate of about 30 a day, and as the remaining eggs age, they get less adept at one of their critical jobs — dividing their 46 chromosomes in half. Eggs don't do this until after they're penetrated by a sperm....