A study of 97 healthy non-smoking men aged from 22 to 80 has demonstrated that, as they age, men's semen quality declines. There was a continuous reduction in sperm motility (movement) and semen volume and the proportion of men with abnormal semen volume, sperm concentration and motility increased significantly across the age decades.
The research, from a team in California, confirms that men as well as women have a biological clock even though it may not start ticking as abruptly as women's.
One of the lead researchers, Dr Brenda Eskenazi, Director of the Center for Children's Environmental Health Research at the University of California at Berkeley, said: "We measured semen volume, sperm concentration, sperm motility and progressive motility (the ability of sperm to move forward) in men with no known fertility problems and we found significant age-related decreases in semen quality, most notably for semen volume and sperm motility.
"However, unlike women, there appears to be no evidence of an age threshold, but rather a gradual change over time. Because semen quality is generally considered to be a proxy for fertility our findings suggest that men may become progressively less fertile as they age.
Over a quarter of cases of infertility are known to be due to male factors. Dr Eskenazi, who is Professor of Maternal and Child Health and Epidemiology, said that understanding the effect of male age on fertility had become increasingly significant in public health as a growing number of men are choosing to father children at older ages than in the past. In the USA, for example, the birth rate for fathers aged between 35 and 54 has risen by nearly a quarter since 1980.
Dr. Andrew Wyrobek, head of the Health Effects Genetics Division at Lawrence
Contact: Margaret Willson
European Society for Human Reproduction and Embryology