Sperm concentration has decreased by 52.4% in men from North America, Europe, Australia and New Zealand, and in recent years the trend has shown no signs of stabilization. And all this has happened in just 40 years .
The study has been published in the journal Human Reproduction Update and has been carried out by screening 7,500 studies and conducting a meta-regression analysis in 185 studies.
Causes?
The Hadassah Braun School of Public Health and Community Medicine at Hebrew University and the Icahn School of Medicine at Mount Sinai have conducted this study that has analyzed sperm concentration trends in Western men between 1973 and 2011.
Despite the staggering decline in Western men, this decline was not seen in men from South America, Asia, and Africa, where the number of studies has been less .
Although this research does not assess the causes of the observed decline , this count is probably associated with environmental factors and lifestyles, including prenatal exposure to chemicals, and that of adults to pesticides, smoking, stress and obesity.
As Hagai Levine , lead author and chief of the Environmental Health Area at the Hadassa Braun School of Public Health and Community Medicine, at the Hebrew University of Jerusalem School of Medicine, explains:
Given the importance of sperm concentration for male fertility and human health, this study is an urgent wake-up call for researchers and health authorities around the world to investigate the causes of this steep decline, in order to prevent .
According to Jaime Mendiola , one of the authors of the work and researcher in the Public Health and Epidemiology group of the University of Murcia (UMU):
The decrease in sperm concentration since 1992 is known, but the issue remains controversial due to the limitations of previous studies. However, this new study has a broader scope and uses rigorous meta-regression methods, which makes it possible to adequately address the reliability of the estimates of the studies, and can also take into account other factors that could explain this decline, such as age, abstinence time, and the selection of the study population.