Sperm counts more than halved since 1970s, and keep declining: study

An analysis of samples taken from over 40,000 people across the globe has shown an alarming downward trend in sperm counts.

An analysis of hundreds of studies covering data from over 50 countries across six continents has shown an alarming downward trend in sperm counts, and researchers are warning that the decline could have far-reaching implications not just for fertility, but also for overall health and mortality.

The analysis was published in the Human Reproduction Update and included data collected from just under 43,000 men between 1973 and 2011. In that 40-year span, researchers found that sperm counts more than halved in Western countries like Canada, the U.S., the U.K., and Australia — where sperm declines were the sharpest.

Globally, the authors of the study estimated that average sperm concentration has fallen to 66.4 million per mL from around 92.8 million per mL, meaning that average sperm concentration is declining by around 0.75 per cent each year.

But when researchers selected just Western men who hadn’t had children yet, they found an even more pronounced drop. In 1973, people in this group had an average sperm concentration of 99.0 million per mL, which is higher than the global average at that time. But by 2011, that concentration plummets to 47.1 million per mL, a decline of 1.4 per cent each year.

Western men in this demographic also saw the sharpest drop in total sperm count, which researchers found declined by 59.3 per cent since the 1970s.

Fertile Western men, or people who had known children at the time their sperm samples were taken, saw a similar decline in sperm concentration from an average of 83.8 million per mL in 1977 down to 62.0 million per mL by 2009.

Declines in sperm counts were less pronounced in non-Western countries, but researchers said this could be due to a lack of historical data.

Researchers did find that the trend of declining sperm counts has been accelerating over time. When the authors of the study looked at data collected globally since 1972 vs. data collected only since 2000, they found that recent sperm concentrations were declining about two times faster than they once were.