Sperm counts around the globe have declined over the past 50 years, a study suggests.
Published in the journal Human Reproductive Update, the meta-analysis looked at 223 studies published between 1973 and 2018 of semen analyses from men across the world. They found that sperm concentration dropped from 101 million per mL to 49 million per mL over the study period, a decline of over 50 percent.
Professor Alan Pacey from the University of Sheffield, spoke positively of the study but remains unconvinced the results reflect a real decline. Speaking to the Guardian, Professor Pacey said
‘Counting sperm, even with the gold standard technique of [the laboratory process] haemocytometry, is really difficult. I believe that over time we have simply got better at it because of the development of training and quality control programmes around the world. I still think this is much of what we are seeing in the data.’
The study also only looks at sperm concentration, not other factors such as morphology and motility which can also affect fertility.
Lead author of the study, Professor Hagai Levine from the Hebrew University of Jerusalem however believes that due to the extent of the decline, it is likely there are factors such as lifestyle and endocrine disrupting chemicals affecting the foetus in the womb that may explain the observations.
- Hagai Levine, Niels Jørgensen, Anderson Martino-Andrade, Jaime Mendiola, Dan Weksler-Derri, Maya Jolles, Rachel Pinotti, Shanna H Swan, Temporal trends in sperm count: a systematic review and meta-regression analysis of samples collected globally in the 20th and 21st centuries, Human Reproduction Update, 2022;, dmac035, https://doi.org/10.1093/humupd/dmac035