The study by Dr David Greening, from Sydney IVF, involved 118 men who had fertility problems. All men had significant amount of sperm DNA damage equivalent to 34 percent. The men were told to ejaculate daily for one week.

Dr Greening told delegates of the European Society of Human Reproduction and Embryology in Amsterdam that doing so reduced the sperm DNA damage from 34% to less than 26% in 81 percent of the participants.  Sperm motility also seemed to increase in the seven-day period.

"It seems safe to conclude that couples with relatively normal semen parameters should have sex daily for up to a week before the ovulation date," Dr Greening stressed. "In the context of assisted reproduction, this simple treatment may assist in improving sperm quality and ultimately achieving a pregnancy."

Dr Greening also said that men are destined to breed when young and it was best to have lots of sex during the time of a woman's ovulation so as to increase the chances of conception.

"Further research is required to see whether the improvement in these men's sperm quality translates into better pregnancy rates, but other, previous studies have shown the relationship between sperm DNA damage and pregnancy rates," Dr Greening concluded.

Damage to sperm DNA is a concerning issue for most fertility specialists. The theory is DNA damaged sperm cannot fertilize the egg. If sperm are preserved for too long in the testes, experts feel the chances of DNA damage are greater because sperm are attacked by free radicals.

The above study, though relatively small, adds to evidence that frequent sex keeps perm healthier and increases the chances of pregnancy.