Shafaqna Health:Something keeps happening to men’s hormones. Across nearly 50 years and five countries, testosterone levels have fallen sharply — and researchers say it may signal a wider crisis in male reproductive health.
In a new analysis presented at the annual meeting of the European Society of Human Reproduction and Embryology in London, researchers reported that average total testosterone levels in men fell by 54 percent between 1972 and 2019.
The work, led by Prof Hagai Levine of the Hebrew University-Hadassah Braun School of Public Health and Community Medicine in Israel, drew together six long-running studies that had repeatedly measured testosterone over time. Together, the studies included 118,593 men from Israel, the United States, Brazil, Finland and Denmark.
We saw an over 50% decline in total testosterone over this time period,” Levine told The Guardian. “It reflects a more than 1% decline each year, so this is not a fluke, this is not a statistical error.”
A Serious Decline
Scientists have been warning for years that men’s reproductive health may be in decline. Earlier studies pointed to falling sperm counts, while doctors have also tracked links between low testosterone, obesity, diabetes and poor metabolic health. This new analysis adds another signal: across nearly five decades, testosterone levels appear to have fallen far more steeply than researchers expected.
Testosterone is a complex hormone that affects much more than just fertility. It helps regulate sperm production and sexual desire, but it is also tied to muscle mass, bone density, mood, energy levels and metabolism. A sustained fall in testosterone, if confirmed, could therefore be a signal not just about reproduction but about men’s general health.
Testosterone levels can change naturally over a man’s life, and lower levels aren’t automatically a sign of disease. But a sharp population-wide drop across generations is different from ordinary aging. It may suggest that more men are being exposed to conditions that suppress testosterone, from obesity and diabetes to other pressures in the modern environment.
The new analysis focused on longitudinal studies, meaning studies that tracked testosterone measurements across multiple points in time rather than capturing a single snapshot. That type of comprehensive study design gives the research more weight than a simple comparison of unrelated groups.
