The Male Biological Clock

The Early Show, medical correspondent Emily Senay
CBS/The Early Show
A lot of reports warn of the risk of conceiving a child as an older mother, but there is new evidence that a man's biological clock ticks just as loudly as a woman's.

The Early Show medical correspondent Emily Senay explains that the study in the Journal of Urology suggests older fathers have similar risks as older mothers of producing children with greater chances of birth defects, such as Down syndrome, and they also lose their ability to conceive.

The report found men over 40 years of age were twice as likely to have a child with down syndrome than those less then 20 years old.

It was always thought in the past that a woman's age was the sole determining factor in birth defects, such as Down syndrome, says Dr. Senay. But the new report adds to the growing body of evidence that late fatherhood is a factor when it comes to the health of a baby.

Previous studies have shown a link between paternal age and schizophrenia; and paternal age and a birth defect known as Achondroplasia.

Researchers in this latest study were able to look at a large number of births to older women in New York State over a 14-year period. They found a dramatic increase in the number of older parents in general, and saw the greatest increase in the number of Down syndrome cases where the father and mother were both over 40.

Currently, Dr. Senay explains, the emphasis is on counseling parents only if the woman is older. But the idea that sperm quality decreases as a man ages underlines the importance of older couples being aware of that possibility, and the risk of birth defects.

Screening can be done at a very early stage to detect genetic abnormalities. The researchers say that prenatal counseling, if either parent is over 40, is probably a good idea.

Another recent study showed that sperm lose some of their mobility in older men, which decreases the chances of conceiving.

Researchers found the risk of fertility problems due to sperm mobility for a man increases with age from 25 percent at the age of 22; 60 percent at the age of 40; and it is 85 percent at the age of 60.

Other studies have showed that damage to sperm cells becomes more common as a man ages, and the natural process by which damaged sperm die and are flushed out slows down, too.

As far as conceiving a child goes, Dr. Senay says the science of fertility has come a long way. It's a subject of some controversy, but couples in their 60s have had success conceiving.

Dr. Senay says many young and old couples who have problems conceiving have a wide range of options available, depending on the nature of their problem.