Daily sex keeps a man's sperm spry and is recommended for couples wanting a baby, according to new research.
Having regular sex clears sperm from the testicles and prevents the natural build-up of DNA damage, Australian scientists found.
They said that would-be fathers should copulate once a day for a week before their partner is ready to conceive. However, getting carried away and having sex more often risked a man's sperm count falling too low.
Fertility doctors disagree about whether or not men should refrain from intercourse for a few days before their partner ovulates. Men undergoing IVF treatment are routinely told to stop having sex to avoid a drop in sperm count.
The new research suggests, however, that rather than reducing the chances of conception, daily sex can increase it.
DNA damage lessened in the sperm of men who had daily sex: "old" sperm was cleared and replaced by fresh cells.
Daily sex also seemed to make the sperm more active, or motile, which is known to improve fertility.
Damage to sperm DNA is mainly due to destructive oxygen molecules generated naturally by cells in the body.
Dr David Greening, from the Sydney IVF clinic in Wollongong, said: "Keeping the river flowing means the sperm doesn't hang around so long and become damaged. There's less time for vandalism. We advise couples to try to work out when the woman's ovulating and have lots of sex."
Dr Greening's team studied 118 men who had higher than normal DNA damage to their sperm, as assessed by the DNA Fragmentation Index (DFI). Men with more than 15 per cent of their sperm damaged were eligible for the trial. At the Sydney clinic, a DFI of less than 15 per cent is defined as "excellent quality" sperm. More than 29 per cent is "poor".
The men were instructed to ejaculate daily for seven days and make no other treatments or lifestyle changes.
On the seventh day, 96 men (81 per cent) were found to have experienced an average 12 per cent decrease in sperm DNA damage. "More men moved into the 'good' range and out of the 'poor' or 'fair' range," said Dr Greening.