Paris. Sperm concentration, one of the factors in male fertility, has declined significantly across the globe in recent decades, according to a study published yesterday.
“Sperm concentration decreased significantly between 1973 and 2018”, summarize the authors of this work published in the journal Human Reproduction Update and made by compiling some 40 previous studies.
This publication is of an unprecedented magnitude on the subject, although it confirms the conclusions of a previous investigation by the same team, led by the Israeli epidemiologist Hagai Levine, which was published in 2017 and had been the subject of various criticisms, in particular because its results only affected some western countries.
This time, after incorporating more data, the authors can conclude that the downward trend also affects South America, Asia and Africa.
“In addition, the data suggest that this global decline continues at an accelerated rate since the beginning of the 21st century,” they point out.
The amount of sperm is one of the factors that affect male fertility, but it is not the only one.
Their mobility also plays a crucial role, but this characteristic is not measured in this study. For this reason, it cannot be concluded that there is a general decline in male fertility, although the research provides elements in this sense and adds to other works that have analyzed the causes of this trend.
Possible causes of this phenomenon include “obesity, lack of physical activity, pollution and exposure to chemicals in the environment,” recalled endocrinologist Channa Jayasena.
This expert from the Imperial College, who did not participate in the study and spoke before the British Center for Media Sciences, praised an “important” work.
Other researchers, already skeptical of the 2017 study, qualified the conclusions of this new publication, considering that it did not resolve all the shortcomings attributed to the previous one.
“I continue to doubt the quality of the studies, particularly the older ones, on which this new analysis is based,” andrologist Allan Pacey told Afp, without questioning the way in which the authors carried out their compilation.
According to him, the evolution of the sperm rate could reflect increasingly reliable measurement techniques, not reality itself.
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