Controversy exists as to whether men on Earth are becoming less fertile than in decades prior. One key measure of fertility is the motile sperm count: the sheer number of sperm which are motile. A rough guide is that it takes around 20 million motile sperm to cause a pregnancy within 12 months of “trying.”
But in a recent research article, it was discovered that the total motile sperm count (TMSC) had fallen from 2019 to 2022 — at least in the bottom 75% of sperm donor candidates:
[the top quartile, Q4, has been cropped out of the image above]
At left in blue are the bottom three quartiles of all of the 6,758 donor candidates, and the right side in red is for the accepted donors who had met all of the parameters required for acceptability. Notice that their vertical scale is higher. Of interest is the “lowest fourth” of the candidates at bottom left, as their 2022 values dropped very low.
Because the confidence interval for 2022 — i.e., the vertical blue line running through the blue dot for 2022 — does not encompass the mean value of 2017 (blue dot in 2017), then that means they experienced a significant drop in motile sperm counts from all prior years: Something is harming the fertility of this “lowest fourth” of men.
While drops are noted for the other two quartiles shown, they are drops from a recent peak in 2019, and the 2022 values are not significantly different from the value back in 2017. This is not true for the “lowest fourth” of men though.
Evidence suggests that something in the environment is harming sperm motility. Big changes in many things have occurred since 2019, making it difficult to pin down which individual thing, or individual mix of things, is responsible for the predominant part of the recorded drop in total motile sperm count (TMSC).
For the lowest fourth of donor candidates, there appears to be something that happened to them — beginning at the end of 2020 or in early 2021 — which ultimately dropped their TMSC by a lot. Because the COVID shots were first given broadly in 2021, they are a prime suspect for the drop in TMSC for this “lowest fourth” of men.
Reference
Lassen E, Pacey A, Skytte AB, Montgomerie R. Recent decline in sperm motility among donor candidates at a sperm bank in Denmark. Hum Reprod. 2024 Jun 4:deae115. doi: 10.1093/humrep/deae115. Epub ahead of print. PMID: 38834185. https://pubmed.ncbi.nlm.nih.gov/38834185/