"Please, darling, we must - the doctor says so"

A study by Australian researchers of men attending a fertility clinic has revealed that the genetic defects in their sperm fell substantially after they were encouraged to have sex each day.

The researchers from Sydney University have found that frequent sexual activity improves the genetic quality of sperm and that may help some couples conceive.

It seems around a fifth of men have sperm with significant DNA damage.

It is quite common for fertility specialists to advise men trying for a baby to abstain from sexual activity for two to three days, because it boosts the number of sperm they produce.

However, this latest finding suggests that men who have healthy sperm counts but poor quality sperm can improve the genetic material in the cells by engaging in sex more often.

Sperm, which are genetically damaged, can reduce the chances of a sperm fertilising an egg, and can lead to the formation of an embryo that fails to implant properly or is miscarried.

For the study Dr. David Greening, a fertility specialist at Sydney IVF, studied 42 men whose sperm had high levels of genetic damage.

All of the men were in partnerships where the couples had a history of recurrent miscarriage or failed IVF treatment.

Tests taken after three days of sexual abstinence revealed 30.8% genetic damage in the men's sperm.

The men were then told to engage in sexual activity daily for a week and were tested again.

While tests showed that their sperm counts fell by nearly one third, genetic damage also fell, on average by 12.8%, in 37 of the men.

Tests on the remaining five men showed their sperm had slightly increased genetic damage.

Dr. Greening says he believes the longer sperm are held in the tube that leads from the testicles, the more genetic damage they accumulate from free radicals circulating in the body.

Greening says he is convinced that ejaculating more frequently, improves sperm DNA damage in most men by a 'decent amount'.

Other experts agree and say ejaculating every day prevents the sperm being in the reproductive tract for too long, so they are exposed to less damage and this could mean better quality sperm.

The Sydney University team presented their research this week at the American Society for Reproductive Medicine conference.