Men’s average testosterone levels have decreased by 54 percent between 1972 and 2019, according to research presented at the European fertility congress ESHRE in London, UK. Researchers are now warning that this trend could have far-reaching consequences for both fertility and public health.

The new meta-study is based on six long-term studies involving a total of 118,593 men from Israel, the USA, Brazil, Finland, and Denmark. All the studies showed a decline in testosterone levels, and when their results were combined, the average decrease was estimated at 54 percent between 1972-2019.

According to Professor Hagai Levine at Hebrew University-Hadassah in Israel, this is a clear and long-term trend.

“We are seeing a decrease of more than one percent per year. This is not a coincidence or statistical anomaly, but a very strong trend,” he told The Guardian.

Obesity and Diabetes

Testosterone is the hormone that affects sperm production, sexual drive, muscle mass, bone density, energy levels, and metabolism. Decreasing levels can therefore have devastating consequences for male fertility and general health.

Researchers point to the rising prevalence of obesity and diabetes as likely explanations for part of the trend. At the same time, environmental factors have also been highlighted, including endocrine-disrupting chemicals found in everyday products and effects tied to a warmer climate.

The study was presented at the annual congress of the European Society of Human Reproduction and Embryology (ESHRE) and is expected to contribute to the ongoing scientific debate about male fertility and the factors behind its long-term decline.

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