Once a man passes the age of 24, the older he is, the longer it takes him to make his partner pregnant, regardless of her age, reported The Associated Press, according to the results of a recent research.
A decline in male fecundity - the likelihood of achieving pregnancy within a certain period of time - has never before been confirmed or quantified in the general population, experts said.
The research, published Tuesday in the European Journal Human Reproduction, provides the first clear evidence that the age of a man, as well as that of a woman, could be an important factor.
"It tells us that, to some degree, men as well as women have a biological clock that starts ticking as they get into their 30s," said Chris Ford of St. Michael's Hospital of Bristol, England, who led the study.
"It also indicates that paternal age is another factor to be taken into account when doctors are looking at the prognosis for infertile couples," Ford said.
The study examined whether men become less fecund as they get older, as opposed to less fertile.
Fertility refers to the ability to produce a baby, while fecundity refers to the ability to do it within a certain period of time. If it takes a man 20 years to make his partner pregnant, he is fertile but not very fecund.
"Fecundity is a critical thing because, as the female ages, her ability to conceive declines dramatically. And if the man is not fecund, by the time he can impregnate his partner it is too late because she is too old," said Dr. Christopher Barratt, a British fertility expert.
The research involved 8,500 British couples whose pregnancies were planned and successful, said the AP.
It found that the probability it would take more than a year to conceive nearly doubled from about 8 percent, when the man was under 25, to about 15 percent when he was over 35, added the agency.
The chance of a man making a woman pregnant within a year of trying decreased by 3 percent for every year he was over the age of 24.
The chance of impregnating a woman within six months declined by 2 percent for each year he was over 24.
"It shows what we've suspected for a long time, and it all makes scientific sense," Barratt said. "The evidence of declining male fertility has been based on indirect measures - cutting up the testes and seeing the number and quality of sperm. This is direct evidence." - Albawaba.com
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