Madrid, Spain ? New research suggests there is little value in couples abstaining from sex to improve their chances of conceiving by saving sperm for the woman’s most fertile time of the month.

In a study to be presented today at a European fertility conference, Israeli scientists provide the strongest evidence yet that men with low sperm counts can significantly reduce sperm quality by holding back for longer than a day or two.

They found that the performance for men with normal fertility tests remained the same whether they abstained from sex for one, two or 10 days before providing a sample.

“Long residence in the male reproductive tract might in some cases mean the sperm do worse, perform worse, than they could do if they abstained less,” said the study’s leader, Dr. Eliahu Levitas of Ben-Gurion University in Israel.

The finding appears to challenge the role of abstinence in male infertility treatment. World Health Organization laboratory guidelines recommend that men seeking fertility treatment refrain from sex for between two and 7 days before providing a sample for analysis.

In the new study, to be presented at the annual conference of the European Society of Human Reproduction and Embryology, Levitas’ group analyzed more than 7,200 semen samples from about 6,000 men undergoing routine fertility investigations.

More than 4,500 of the samples were normal, while the rest showed varying degrees of low sperm counts.

The men abstained from sex for up to two weeks before giving their samples.

In men with low sperm counts, the researchers found the volume of semen increased after prolonged abstinence, but the quality got gradually worse the longer the men held back.

The number and proportion of motile sperm, meaning active and moving sperm, fell significantly from day two onwards, reaching a low at day six and remaining low.

The percentage of malformed sperm also increased after just a few days of abstinence, the scientists found.