Study Finds Men’s Testosterone Levels Fell 54% Over 50 Years

Researchers presented an analysis at an international reproductive‑medicine congress in London that shows average testosterone levels in men have dropped about 1% per year since the early 1970s, amounting to roughly a 54% decline over the past five decades. The study, coordinated by Professor Hagai Levine of the Hebrew University of Jerusalem, pooled data from more than 118,000 men in Israel, the United States, Brazil, Finland and Denmark between 1972 and 2019.

Authors warn the trend could signal a looming crisis for male reproductive health, potentially affecting fertility, muscle mass, bone density, metabolism and mood. They cite rising obesity, diabetes and exposure to environmental chemicals as possible contributors. However, the analysis has not yet undergone peer review, the data are largely from developed nations, and the confidence intervals around the estimates are wide, meaning the true magnitude of the decline could differ from the headline figure.

Experts caution that a lower average does not automatically translate into widespread infertility and call for further research before drawing definitive conclusions.