Study: Men Have Biological Clocks

L O N D O N, July 31 -- Men have a biological clock too, Britishresearchers said today.

Like women, their ability to procreate decreases with age.

Scientists at Bristol and Brunel universities in Englandhave discovered that when a man is less than 25 years old thechance of his partner not getting pregnant after a year oftrying is about 8 percent.

By the age of 35 it nearly doubles to 15 percent.

“To our knowledge this is the first study to demonstrateepidemiologically that male fertility declines with age,” Dr.Chris Ford, of the University Division of Obstetrics andGynecology at St. Michael’s Hospital in Bristol, told Reuters.

“People have long suspected that male fertility declineswith age but there wasn’t any definitive demonstration of it,”he said in a telephone interview.

Ford and his colleagues studied 8,500 couples living inEngland and evaluated the impact of the man’s age on the time ittook them to conceive. Their research is published in thejournal Human Reproduction.

“It tells us that, to some degree, men as well as womenhave a biological clock that starts ticking as they get intotheir 30s and it also indicates that paternal age isanother factor to be taken into account when doctors are lookingat the prognosis of infertile couples,” said Ford, a spermphysiologist.

The researchers do not know why a man’s age influencesfertility but they said three factors could be significant.

“The frequency of intercourse declines very abruptly afterthe first year of the relationship but there is also theindependent fact of the man’s aging. As men age, couples tend tohave sex less often and if they do that the chance of having sexduring the [woman’s] fertile period is less,” Ford said.

Older men are also more likely to experience changes intheir testes which could have an impact on the quality of sperm,and they have a higher chance of suffering damage fromenvironmental factors or disease.