Questionable study results: men have fewer and fewer sperm

Sharp decline: European men have fewer and fewer sperm
A study was published several years ago, showing that the French have fewer and fewer sperm. According to a recent study, their peers from other European countries are not doing better. According to the latest findings, the number of sperm per milliliter of sperm in men from western countries has dropped dramatically.

Men from western countries produce less sperm
According to a recent study, the number of sperm from men in Europe and other western regions continues to decline. As the researchers report in the journal "Human Reproduction Update", the number of sperm per milliliter of sperm in men from western countries fell by 52.4 percent between 1973 and 2011. According to the scientists, the decrease in the total number of sperm per ejaculation is as high as 59.3 percent.

Pollution from environmental toxins
Earlier research had shown that the number of sperm in men in some European countries has decreased.

This decline has been linked, among other things, to pollution from environmental toxins.

Studies have also shown that a father's high-fat diet, too much cola and marijuana harm the sperm.

And cell phones in their pants also seem to have a negative impact on the number of sperm.

Urgent wake-up call for experts
The head of the current study, Hagai Levine from Hebrew University in Jerusalem said, according to a report by the British newspaper "The Guardian": "The results are quite shocking."

"Given the importance of sperm for male fertility and human health, this study is an urgent wake-up call for researchers and health officials around the world," Levine is quoted in the Times of Israel.

According to a report by the dpa news agency, Artur Mayerhofer from the BioMedical Center of the Ludwig Maximilians University in Munich, however, considered the results: "Sperm functionality such as motility, but also morphological changes were not considered in this analysis."

“It remains to be seen whether the data can therefore be used to conclude that men have really become more sterile,” says the scientist, who was not involved in the analysis.

tip of the iceberg
According to Mayerhofer, the falling sperm count may just be the tip of the iceberg. In his opinion, the trend that the work points to is questionable:

an increase in testicular tumors, cryptorchidism (abdominal testicles) and other problems as well as a connection with general morbidity and mortality.

In order to arrive at their results, Levine and his colleagues from Israel, Brazil, Denmark, Spain and the USA evaluated 244 sperm counts from 185 studies that had been carried out on almost 43,000 men.

A distinction was made between participants from countries with a western lifestyle (Europe, North America, Australia and New Zealand) and the rest of the world (especially Asia, Africa and South America). 28 percent of the data came from the latter.

The decline is strong and persistent
Statistically, the sperm count per milliliter in Western men decreased by 1.4 percent per year from 1973 to 2011, and in the total number per sperm sample even by 1.6 percent.

These figures are said to refer to those men who have not been determined to be fertile. For those with children, the annual decrease in the number per milliliter and the total was approximately 0.8 percent each.

No statistically significant trend was identified in the other regions of the world.

"This clear study shows for the first time that this decline is strong and persistent," said co-author Shanna Swan of the Icahn School of Medicine at Mount Sinai in New York, USA, according to the Times of Israel.

The fact that the decline is particularly evident in western countries strongly suggests that external factors such as chemicals and lifestyle "play a causal role in this trend," she said.

According to the researchers, however, the exact reasons for the decline still need to be investigated in order to be able to take countermeasures.

Numerous reasons for a decrease in the number of sperm
According to Stefan Schlatt from Münster University Hospital, who was not involved in the study, the study provided a good basis for discussion. However, the tendency shown is only partially questionable:

"If you look at the concrete numbers, they are still far above the values ​​that the World Health Organization specifies as the lower limit of fertility," said the expert, according to dpa.

Although the number of sperm is decisive in the assessment of fertility, it also plays a role how flexible the sperm are and whether they are possibly deformed. However, this was not considered in the study.

According to the doctor, the reasons for the decrease in the number of sperm are suspected: from the too warm diaper in babies to aspirin to the cell phone in your pocket.

Schlatt sees an important reason for declining fertility that men grow older when they start a family. Because with increasing age the sperm quality drops. (ad)

Author and source information

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