Prolonged stress can reduce sperm quality, according to a new study conducted on Israeli men during, and shortly after, two wars between Israel and Gaza.

The study, presented last month at the Annual Israel Fertility Association Conference in Tel Aviv, indicated that sperm moved more slowly in 37 percent of the 659 samples taken from men during the fighting and up to two months after military confrontations between Israel and the Hamas terror organization, which has sworn to destroy the Jewish state, in 2012 and 2014.

Strong sperm motility is needed for the successful fertilization of an egg.

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“Mental stress is known to have an adverse effect on fertility, but there is little research on the impact of stress on sperm quality,” said Eliahu Levitas, a member of the Ben-Gurion University Faculty of Health Sciences and director of the IVF Unit and the sperm bank at Soroka University Medical Center in Beersheba.

“This study shows that prolonged stress can have an effect on sperm quality.”

He added, “Our reasoning was that even men who heard incoming rocket warning sirens during a conflict experienced stress throughout the day over a longer period. We were surprised to discover that there is a connection between the security situation and the sperm counts.”

The research, undertaken at Soroka and at Ben-Gurion University of the Negev compared the sperm of men who had been under stress — their average age was 32 — with 10,536 samples donated during unstressful periods between 2009-2017.

Israel fought a 50-day war with Hamas in 2014, known as Operation Protective Edge, which saw thousands of rockets fired at Israeli population centers and Israeli forces destroy dozens of cross-border attack tunnels. Two years earlier, the IDF launched the eight-day Operation Pillar of Defense in response to rocket fire.

Last year, a study led by Israeli researchers warned that sperm concentration of men in Western countries has dropped by more than 50 percent in less than 40 years and there is no evidence that the decline is leveling off.