Photo:iStock Sperm and Egg. Digital Composite.
Sperm counts in men from North America, Europe, Australia and New Zealand have halved in less than 40 years, according to new research by the Hebrew University of Jerusalem.
Dr. Hagai Levine, an epidemiologist, analysed the results of 185 studies carried out between 1973 and 2011, involving samples taken from almost 43,000 men.
His team found that there has been a 52.4 per cent decline in sperm concentration, and a 59.3 per cent decline in total sperm count in men. The study also shows that the rate of decline is gathering pace. However, no ‘significant decline’ was observed in Asia, Africa and South America.
Although the researcher behind the study is making apocalyptic warnings about the end of humanity, the results have other, more mundane public health implications. Reduced sperm count is predictive of increased all-cause mortality, and also increases the likelihood of several conditions developing, including testicular cancer.
Dr Levine said: ‘If we will not change the ways that we are living and the environment and the chemicals that we are exposed to, I am very worried about what will happen in the future. Eventually we may have a problem, and with reproduction in general, and it may be the extinction of the human species.’
‘We must take action – for example, better regulation of man-made chemicals – and we must continue our efforts on tackling smoking and obesity.’
There has been some concern in recent years in the medical profession about falling sperm counts but quality research has been difficult to find. This meta-analysis of almost 200 studies from men around the globe addresses this by looking at results between 1973 and 2011 and the conclusion reached is that sperm counts have halved in men from Europe, North America, Australia and New Zealand in the last 40 years.
This has led to headlines suggesting that humankind could become extinct in the future but there are multiple caveats; no significant decline is seen in South America, Asia and Africa, and there is the view that studies showing a decline in sperm count are more likely to be published in scientific journals than those that show the opposite, and early methods of counting sperm may have been inaccurate.
These results should still be treated with caution but they do raise the possibility that factors such as smoking and obesity may be impacting male fertility in a more serious way than previously thought.
Research score: 3/5