Men are more fertile in rainy season, study finds

*Sperm is twice as active in July and August compared to January 

IN spring (March, April and May) a young man’s fancy may turn to thoughts of love, but it’s in summer that his semen is more likely to send him on the path to fatherhood.

New research shows that sperm is more active in the middle months of the year, and twice as active in July and August compared to January, according to a study based on 11 years of data on more than 5,000 men being treated for fertility problems.

According to the study published yesterday in the journal Chronobiology International, seasonal changes in levels of hormones including testosterone may be responsible.

Meteorologists generally define four seasons in many climatic areas: spring, summer, autumn (fall) and winter. These are demarcated by the values of their average temperatures on a monthly basis, with each season lasting three months.

According to Wikipedia, the three warmest months are by definition summer, the three coldest months are winter and the intervening gaps are spring and autumn. Spring, when defined in this manner, can start on different dates in different regions.

In terms of complete months, in most north temperate zone locations, spring months are March, April and May, although differences exist from country to country. (Summer is June, July, August; autumn is September, October, November; winter is December, January, February).

Infertility, defined as the inability to conceive after 12 months of trying, affects around 15 to 20 per cent of couples and progressively increases with age. Male infertility is responsible for about half of cases, and one of the main factors is poor sperm motility.

To reach and fertilise an egg, sperm must wriggle and swim through a woman’s cervix, uterus and fallopian tubes. This movement is known as motility, and men are most likely to be fertile when at least 40 per cent of sperm are moving.

In the study, doctors analysed data collected from 5,188 men attending the Centre for Reproductive Incapacity of the University Hospital of Parma, in northern Italy, looking for possible seasonal pattern in sperm quality. Results show that motility peaked in the summer, and was lowest in the winter.

They also show that the number of men with a motility or movement greater than 40 per cent was 65.3 per cent in summer, and only 50 per cent in winter.

Dr. Alfredo De Giorgi, who led the study confirmed: “We have shown the existence of a seasonal variation in some functional aspects of human semen.”

In seasonal breeders – animals that successfully mate only during certain times of the year – light plays a part in the regulation of reproduction, to ensure that birth occurs at the most favourable time of the year.

In humans, there are also seasonal variations in the sleep cycle as well as in levels of the stress hormone cortisol, teosterone, vitamin D and cholesterol.

A recent study conducted by researchers from Washington State University substantiates earlier claims regarding the connection between endocrine mimickers, such as bisphenol A (BPA), and fertility complications in men and women, according to a report by the Press Association.

New research shows that sperm is more active in the middle months of the year, and twice as active in July and August compared to January, according to a study based on 11 years of data on more than 5,000 men being treated for fertility problems… Results show that motility peaked in the summer, and was lowest in the winter. They also show that the number of men with a motility or movement greater than 40 per cent was 65.3 per cent in summer, and only 50 per cent in winter.

Hormone disruptors, found in a variety of sources, continue to pose a very real threat to humans as they alter the normal functioning of hormones, interfering with signaling processes that tell our tissues what to do.

Published in the online journal Public Library of Science Genetics, this latest study sheds light on the way xenoestrogens, synthetic versions of estrogen used in women’s birth control pills, affect sperm counts in men, disrupting their ability to produce.

Researchers from the U.S. obtained their results after they exposed newborn male lab mice to doses of the plastics chemical (bisphenol A) and estradiol, a synthetic form of estrogen used in contraceptives, in their food.

Men, as well as the general population, are exposed to estradiol through public drinking water, as most wastewater treatment plants are still lacking the equipment needed to filter out low concentrations of pharmaceuticals. Learn more: