LONDON - Having sex every day improves the quality of men's sperm and is recommended for couples trying to conceive, according to new research.

Until now doctors have debated whether or not men should refrain from sex for a few days before attempting to conceive with their partner to improve the chance of pregnancy.

But a new study by Dr David Greening of Sydney IVF, an Australian centre for infertility and in vitro fertilisation (IVF) treatment, suggests abstinence is not the right approach. He studied 118 men with above-average sperm DNA damage and found the quality of their sperm increased significantly after they were told to ejaculate daily for seven days.

On average, their DNA fragmentation index - a measure of sperm damage - fell to 26 percent from 34 percent, Greening told the European Society of Human Reproduction and Embryology in Amsterdam on Tuesday.

Frequent sex does decrease semen volume but for most men this is not a problem.  

"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," he said in a statement.

"In the context of assisted reproduction, this simple treatment may assist in improving sperm quality and ultimately achieving a pregnancy."

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.