Men seeking to become a dad should have sex each day for a week before their partner ovulates to improve the genetic quality of their sperm, new Australian research suggests.
Until now fertility specialists have debated whether refraining from sex in the days before attempting to conceive with their partner could increase a man's chances of fathering a child.
A study by David Greening, a specialist in reproductive endocrinology and infertility at Sydney IVF, has found that ejaculating daily substantially improves the genetic quality of sperm, without lowering sperm counts enough to impair fertility.
At the annual meeting of the European Society of Human Reproduction and Embryology in Amsterdam this week, Dr Greening said the findings could have important implications for couples trying to conceive spontaneously and those undergoing assisted reproduction.
"These results may mean that men play a greater role in infertility than previously suspected, and that ejaculatory frequency is important for improving sperm quality, especially as men age and during assisted reproduction cycles," he said.
Ejaculating daily substantially improves the genetic quality of sperm, without lowering sperm counts enough to impair fertility.
Dr Greening studied 118 men with above-average sperm DNA damage and found their sperm quality increased significantly after they were told to ejaculate daily for seven days, compared to three days abstinence.
On average, their DNA fragmentation index - a measure of sperm damage - fell from 34 per cent (poor quality) to 26 per cent (fair). Ninety-six men recorded about 12 per cent decrease in sperm DNA damage, putting them in the good range.
Dr Greening said it was likely frequent ejaculation improved the quality of sperm by reducing the length of time they were exposed to potentially damaging molecules called reactive oxygen species in the testicular ducts and epididymis.
However, 22 men recorded an increase in damage of 10 per cent on average and Dr Greening said these men may have a different explanation for their sperm DNA damage.
Couples with relatively normal semen parameters should have sex daily for up to a week before ovulation, he said.
"In the context of assisted reproduction, this simple treatment may assist in improving sperm quality and ultimately achieving a pregnancy."
Further research was required to see if improved sperm quality led to better pregnancy rates.
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