Men May Have Biological Clocks, Too
Some researchers say a man's age may affect not only his ability to father a child -- but the health of his offspring.
Aging Dads: What Goes Wrong continued...
In a French study of nearly 2,000 men published in 2005 in the journal Fertility and Sterility, doctors concluded that even in couples undergoing IVF an aging father could figure into the pattern of pregnancy failure, more than previously thought.
But it's not just the idea of making fewer babies that is of concern. The new research is also tampering with conventional fertility wisdom, which has long asserted that because new sperm is made daily, male fertility remains untouchable.
And while the notion of unending sperm production hasn't changed, some researchers now believe that as a man ages, the task of churning out that daily supply is a little like trying to make a fresh batch of macaroni in a worn-out pasta machine.
In short, while the ingredients may be fresh, the mechanism that puts it all together gets slower and works less efficiently with age. And that means far fewer perfect macaroni -- and sperm -- to show for it.
Effects of Aging
"There is definitely evidence of weaknesses in the DNA of sperm as a man ages. And this could be the result of a weakness anywhere in the sperm-making system, from the copying mechanisms necessary to turn out new sperm every day, to the natural ability of the body to correct mistakes in that copying process, or really, any step along the way; any or all could become defective as a man ages," says Kleinhaus.
While female fertility may be limited because women are born with a limited number of eggs, Kleinhaus says it's boosted by the fact that the DNA-copying process is complete at birth -- and not generally subject to mistakes along the way.
Conversely, while men may still be able to manufacture that daily supply of sperm -- regardless of age -- Kleinhaus says they remain vulnerable to bloopers, errors, and DNA foul-ups with each and every copy that's made.
"This just doesn't impact the rate of conception, we believe it can impact the health of the baby or even the health of the pregnancy itself," says Kleinhaus.