Men who suffer fertility problems because of low sperm quality may be able to improve their chances of fatherhood by having sex every day, research has suggested.
While those trying for a baby are often told to refrain from ejaculating too often to protect their sperm count, Australian scientists have shown that this can be counterproductive and may lower male fertility.
Among men whose fertility problems stem from genetic damage to their sperm rather than a low sperm count, abstaining from sex can make their difficulties worse, research led by David Greening, of Sydney IVF, has shown.
The pilot study of 42 men whose sperm showed significant DNA damage found that daily ejaculation reduced this by 12 per cent. While the results are preliminary and no direct effect on fertility has yet been measured, they suggest that certain men could benefit from having sex more often, or from abstaining less before providing semen for use in IVF.
Dr Greening, who presented his results at the American Society for Reproductive Medicine conference in Washington yesterday, said: “I’m convinced that ejaculating more frequently, ie daily, improves sperm DNA damage in most men by a decent amount.
“Prior to IVF, for example, men are abstaining a lot more than normal and perhaps sperm DNA increases more than usual. Men think if they abstain for longer times before, say, ovulation that their sperm will be better. [There may be] more volume and numbers but DNA damage may increase.”
Abstaining from sex does increase the number of sperm that are ejaculated, and this has led to advice that couples trying for a baby should have sex every two to three days.
Longer periods of abstinence, however, achieve little because while the quantity of sperm might increase, its quality declines. As sperm is produced, it is stored in the epididymis at the top of the testicle, but the longer it sits there the more damage it accumulates from exposure to free radicals.
Regular ejaculation empties this sperm reservoir, making sure that newly produced sperm of higher genetic quality can get out.
Allan Pacey, a senior lecturer in andrology at the University of Sheffield, said that clearing the reservoir was more important when sperm had high levels of genetic damage. “If you get above 30 to 40 per cent damaged DNA, a man is highly likely to be infertile,” he said. “When you put people on a daily ejaculation regime, it reduces that figure for DNA damage. If you can go from 30 per cent down to 20 per cent that is quite a big shift, that should have implications for fertility.
“There is a trade-off between genetic damage and quantity, so when a couple are first trying to get pregnant a wait of two to three days is probably advisable. But if you are a guy who has high DNA damage and a decent sperm count, it is probably in your interest to ejaculate every day.
“I remember one couple in which the woman would only let the man ejaculate when she was in her fertile period, so the poor chap was going without for almost a month at a time.
“Even leaving aside the frustration that must have caused, it would have had no benefits.”