A new meta-analysis of global sperm counts found that the average man today has only half as much sperm as he did 50 years ago.
The analysis, published in November by the Oxford University Press, found that average sperm count has fallen from 101 million/ml in 1973 to just 49 million/ml in 2018. Data was pulled from men on six continents and the authors found that the decline was present across all regions of the globe.
New sperm meta-analysis. Big takeaways:
• 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— Ben Wilson (@BenWilsonTweets) November 30, 2022
A prior meta-analysis by the same researchers found that sperm count had decreased drastically over time in North America, Europe and Australia, but the new analysis was the first to also include Africa, Asia and Latin America. The authors of the paper whittled down a sample of 2,936 abstracts and 868 full articles to 44 estimates of sperm concentration and total sperm count from 38 studies, which met their protocol.
After combining the new data with the previous analysis, the researchers had 288 estimates based on semen samples taken between 1973 and 2018.
Sperm count is not a perfect proxy for fertility itself, according to the paper. Beyond a range of 40-50 million/ml, additional sperm does not necessarily increase a man’s fertility. However, there is a rapid drop-off in fertility for men beneath this threshold, they wrote.
Data indicated that the decline steepened beginning in the year 2000. (RELATED: New Jersey Middle Schoolers Shown Video Endorsing Hormone Therapy)
The authors did not go into detail on what may be causing the decline. There are a number of medical conditions which are associated with low sperm counts, but there are also various environmental and lifestyle factors, some of which have become more prominent in recent decades.
Environmental causes of low sperm count can include exposure to industrial chemicals, radiation or x-rays and overheating of the testicles, according to the Mayo Clinic. Lifestyle causes include alcohol use, drug use, depression, smoking and obesity. Obesity rates, drug use and sedentary lifestyles have all increased during the time the sperm count analysis was conducted.