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DNA in sperm fragments as men age, increasing the risk of infertility or of babies being born with anomalies such as dwarfism, scientists at the University of California, Berkeley, and Lawrence Livermore National Laboratory concluded.
"We know that women have a biological time clock," said study co-author Brenda Eskenazi of the university's School of Public Health.
Clock ticking for men as well
"Our research suggests that men, too, have a biological time
clock, only it is different. Men seem to have a gradual rather than
an abrupt change in fertility and in the potential ability to
produce viable healthy offspring."
Earlier research by the same team indicated that sperm counts
decline and sperm loses its ability to move spontaneously and in
straight lines as men age.
The current study, which will be featured this week in an online edition of Proceedings of the National Academy of Sciences, focused on genetic damage or mutations in semen from men of varying ages.
Increased risk of genetic problems
"This study shows that men who wait until they are older to have
children are not only risking difficulties conceiving, they could
also be increasing the risk of having children with genetic
problems," said co-author Andrew Wyrobek of the national lab.
The 97 men that took part in the study were healthy, non-smoking, lab employees or retirees ranging in age from 22 to 80 years old, according to authors.
A supplemental study involving men from the US city of Baltimore indicated that dietary, ethnic, or socio-economic background could exacerbate the effect age has on sperm quality.
Understanding ramifications of paternal age has become increasingly important because of a trend for men to become fathers later in life, according to the study's authors.
The number of men in the US ages 35 to 49 fathering children has risen approximately 40 percent since 1980, while there has been a 20 percent drop in the number of fathers younger than 30, statistics cited by researchers indicated. – (Sapa-AFP)
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June 2006
