Over the past 50 years, human sperm counts appear to have fallen by more than 50% around the globe, according to an updated review of medical literature.
If the findings are confirmed and the decline continues, it could have important implications for human reproduction. Researchers say it would also be a harbinger of declining health in men in general, since semen quality can be an important marker of overall health.
The aim of the study was to examine trends in sperm count among men from all continents. The broader implications of a global decline in sperm count, the knowledge gaps left unfilled by prior analysis and the controversies surrounding this issue warranted an up-to-date meta-analysis.
New sperm meta-analysis. Big takeaways:— Ben Wilson (@BenWilsonTweets) November 30, 2022
• Sperm reduction is not localized, happening globally
• 50% reduction in avg sperm count since 1973
• Following this trend, the average man will not be able to have children unassisted by 2050https://t.co/kCg6ggOia5
Numerous studies have reported declines in semen quality and other markers of male reproductive health. Our previous meta-analysis reported a significant decrease in sperm concentration (SC) and total sperm count (TSC) among men from North America–Europe–Australia (NEA) based on studies published during 1981–2013. At that time, there were too few studies with data from South/Central America–Asia–Africa (SAA) to reliably estimate trends among men from these continents.
This analysis is the first to report a decline in sperm count among unselected men from South/Central America–Asia–Africa.
The data suggest that this world-wide decline is continuing in the 21st century at an accelerated pace. Research on the causes of this continuing decline and actions to prevent further disruption of male reproductive health are urgently needed.
The reason for the decline is unclear although lifestyle and pollution causes appear to be the most likely reasons. Obesity affects fertility, and exposure manmade chemicals that are in plastic, such as phthalates, disrupt the development of the male reproductive system in utero.