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 review, and its conclusions, have sparked a debate among experts in male fertility. Some say the findings are real and urgent, but others say they are not convinced by the data because the methods of counting sperm have changed so much over time that it’s not possible to compare historical and modern numbers.
Nearly all experts agree that the issue needs more study.
“I think one of the fundamental functions of any species is reproduction. So I think if there is a signal that reproduction is in decline, I think that’s a very important finding,” said Dr Michael Eisenberg, a urologist with Stanford Medicine who was not involved in the review.
“There is a strong link between a man’s reproductive health and his overall health. So it could also speak to that too, that maybe we’re not as healthy as we once were,” he said.