By taking a sample of over 6,000 men undergoing fertility treatment, the researchers write their findings in the American Journal for obstetrical and midwifery science, that they have the greatest number of sperm that swim agile and at least with disabilities are produced in the winter and decreased gradually until spring.
"The pattern of the winter and spring sperm matched with increased probability of pregnancy and childbirth to give an explanation of the peak in the fall," wrote study leader Eliahu Levitas, citizens of Israel from Ben-Gurion University, in the Negev, Beer-Sheva.
If there is a pattern, it will be important knowledge "especially for couples with fertility are less in men to overcome fertility treatments".
For these studies, Levitas and his colleagues collected and analyzed 6455 semen of men in their fertility clinic between January 2006 and July 2009. Of these, 4,960 men known to produce normal sperm and 1,495 producing abnormal - for example, slow sperm ,
The World Health Organization (WHO) stipulates that normal semen is containing 16 million sperm per milliliter, as reported by Reuters.
Speaking of the amount, expected to take 70 days for the body to produce sperm cells, and the best are produced in the winter. For example, the average man produces 70 million sperm per milliliter of semen in the winter.
Five percent of that number have very nimble movement, swim faster thus increasing the chances of a couple to get pregnant.
In the spring the amount produced about 68 million sperm per milliliter and only three percent were very agile.
Men are abnormal sperm production, do not show this pattern. They showed a tendency sperm motility slightly better in the fall and normal sperm counts most is seven percent, in the spring.
"Previous studies, mostly in animals also showed similar results, associated with the mating season," said Edmund Sabanegh, urologist from Cleveland, Ohio who was involved in the study.
Animal studies have shown seasonal changes in sperm production and fertility related to many broad factors ranging from temperature, long period of light and dark in the day as well as hormones.
From human studies, recent research suggests that sperm counts are declining worldwide, but it is unknown why, though theories mentioned lifestyle, chemically polluted environment can affect sperm health.
Sabanegh said of course the doctors would not advise him to wait until the spring to prepare the child gets.
"We will continue to encourage them to try to ignore the season and will probably be lucky of care or assistance," he said.
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