Scientists have found more evidence that in men the Biological clock for reproduction also begins to mark beyond 35 years.
A French study with more than 12,200 couples in fertility treatment suggests that pregnancy success declines when the man is over 35 years old.
Previous studies have shown that both natural and assisted conception is difficult if the man is over 40 years old.
European researchers have stated at a Reproductive Health Conference in Barcelona, that the problems are likely to be caused by DNA damage in the sperm. The study was conducted with couples who had sought infertility treatment at the Assisted Reproduction Center in Paris between January 2002 and December 2003. All were given in intrauterine inseminations known as artificial insemination, in which sperm are inserted when the Woman is ovulating. This is done when women have no infertility problems and is less invasive than IVF (when an egg is fertilized in a laboratory dish).
The researchers analyzed detailed data on pregnancies, which allowed them to identify the associated factors in men and women.
As expected, maternal age had an effect on women over 35, who had a higher chance of miscarriage and a decrease in the pregnancy rate.
But the team also found that, when the father was in his last 30 years, miscarriages were more frequent than if the man was younger.
And in men it is over 40, the chances of pregnancy success were even lower.
For the elderly, one third of pregnancies ended in miscarriage and only 10% of treatments ended in pregnancies.
Dr Allan Pacey, a fertility expert at the University of Sheffield and the secretary of the British Fertility Society, said: "There is increasing evidence from a series of studies showing that men are not totally immune to aging reproduction." .
