Male fertility is falling every year in the Western world — and experts blame chemicals and modern lifestyles.
A study of 124,000 men visiting fertility clinics in Europe and the USA found sperm quality reducing by almost 2% per year.
Separate research focusing on 2,600 sperm donors [men with above-normal fertility] showed a similar pattern.
While most men can still father a child, scientists say the human race faces extinction if the trend continues.
It follows a landmark study last year showing a 59% cut in Western sperm counts from 1973 to 2011.
Pesticides, hormone-disrupting chemicals, stress, smoking and obesity are seen as causes, along with too much alcohol, caffeine and processed meat.
The chemicals include some used to make plastics flexible and furniture flame-retardant – which can enter the food chain via plants or animals.
Experts also blame increases in testicular cancer, the number of boys born with one or both testicles missing, and changing testosterone levels.
Scientists in Valencia, Spain,and New Jersey, carried out the first large-scale study of “swimming” sperm, known as the total motile sperm count.
Men were split in to three groups with low, medium and high counts. The TMSC of those in the highest US group declined by 1.8% each year.
The findings are causing alarm at an American Society for Reproductive Medicine meeting in Denver, Colorado, this week.
Co-author Dr James Hotaling said: “There is potential for more men to become infertile and that is concerning.
“It takes two people to make a child.”
Without drastic measures to increase fertility in civilized nations, humanity faces a very real risk of being thrown back into the Middle Ages as 7th century barbarians infest the western world, vastly outbreeding the native inhabitants.
Among American men in the most fertile group, who had more than 15 million moving sperm, this went down by 1.8 per cent for each year of the study.
Between 2002 and 2005, 84.7 per cent of men were in the most fertile group, but this fell to 79.1 per cent between 2014 and 2017.
At the same time, the proportion of the least fertile men rose. Those with poor fertility, from five million swimming sperm to none, increased from less than 9 per cent of the total to 11.6 per cent.
Dr James Hotaling, a co-author of the study, said: ‘We did not expect to see the same fall in sperm quality in Spain and the US. If this trend continues, there is potential for more men to become infertile.’
Commenting on the study, a UK expert, Professor Charles Kingsland, of CARE fertility, said: ‘Our change to a more sedentary lifestyle has no doubt had an effect, as has our diet because men tend to eat far more rubbish than they did a generation ago.’
The second study, led by Icahn School of Medicine at Mount Sinai, New York, involved more than 2,500 sperm donors.
It found that fertility declined over 11 years in Los Angeles, Palo Alto, Boston, Houston and Indianapolis. New York was the only one of the six cities studied to buck the trend.
Sedentary lifestyles are believed to lower sperm production, while cheap and saturated fats found in junk food are known to harm sperm counts.
The chemical bisphenol A (BPA), widely used in plastic wrappers and containers, has been found to be toxic to sperm. Birth rates among American women have been falling for decades, but took a sharp downward turn beginning around 2010.
By 2016, the fertility rate in the US was only 62 live births per every 1,000 women.
Fertility specialists emphasize that male and female biology are approximately equally responsive for any reproductive issues or failures.
Taken together, the recent data on sperm counts and birth rates in the US do not bode well for the stability of the American population, as measured through something called the rate of replacement.
Each mother needs to have an average of 2.1 children in order to ‘replace’ the people who die each year, maintaining an equilibrium in the population.
But in the US, women are having an average of 1.8 children, men are less fertile than they have been for many decades, and – as the baby boomer generation ages – the American mortality rate is set to climb.
James E Windsor, Overpasses News Desk
October 8th, 2018