Global sperm count may not be declining as fast as scientists thought: new research

Don’t count the men out just yet.

New research is challenging recent reports that men’s sperm count is declining globally.

In a study published in the journal Human Reproduction on June 5, researchers at the University of Manchester, Queen’s University in Kingston, Canada, and Cryos International, a Denmark-based sperm bank, collected data from 6,758 men from four Danish cities.

They found that sperm concentration varied significantly from year to year, but did not change drastically over a six-year period – as two influential meta-analyses have recently claimed.

Cryos has been operating for more than 40 years, but limited their research to samples collected between 2017 and 2022. This provided consistent measurements of sperm concentration and motility – referring to how well they swam – as their collection methodologies data have changed over the decades.

“This is to some extent the result of the meta-analysis published by Levine et al. (2023) who proposed that worldwide sperm concentrations had declined by up to 2.64% per year in unselected men since 2000,” said Allan Pacey, professor at the University of Manchester and co-author of the new report.

“We saw no such change and this suggests that in this population of sperm donor applicants, in these four Danish cities, sperm concentrations did not change between 2017 and 2022.”

The researchers found a significant decline between 2019 and 2022, finding a decline in concentration (16%) and mobility (22%) – which “roughly corresponds to the onset of the worldwide COVID-19 pandemic”, said Professor Robert Montgomerie, another collaborator. – author of the study.

“While there is no evidence to suggest that the SARS-CoV-2 virus is directly affecting sperm, we speculate whether the widespread blockages may have led to changes in working conditions, diet and physical activity levels that we already know that they can affect sperm motility. “, Montgomery explained.

Information about the participants’ health and lifestyle profiles was not included in the study, which may explain some of the overall drop rate.

The researchers hope to continue monitoring sperm quality in donor candidates at banks such as Cryos International as a means of tracking changes over longer periods of time.

Said Anne-Bine Skytte, the company’s medical director, who also co-authored the study, “Men who apply to be sperm donors are doing so to help women and couples achieve their family desires.”

“We have no way of knowing how random this sample is in relation to the general (Danish) population, but this study shows that another altruistic outcome of applying to be a sperm donor is how the data can are now used to answer big science questions, like whether sperm counts are falling or not.

“This is an unexpected benefit of their generosity,” Skytte concluded.