Meta AnalysisHumann = 3562022
The Impact of High Ambient Temperature on Human Sperm Parameters: A Meta-Analysis.
Plain-language summary
This meta-analysis set out to work out how high ambient temperature affects sperm quality. It pooled nine studies covering 356 men in Iran, Italy, Thailand, China and Egypt, comparing men exposed to high heat at work or in their climate against men who were not, and it looked at semen volume, sperm concentration, total sperm count, motility and the share of normally shaped sperm. Every one of those measures came out worse in the heat-exposed men. The clearest effects were on the share of normally shaped sperm and on motility. The authors suggest that men exposed to sustained heat need some way of protecting their fertility from it.
Key findings
- High ambient temperature was linked to fewer sperm with a normal shape, the largest of the six effects the review measured.
- High ambient temperature was linked to worse sperm motility.
- High ambient temperature was linked to lower sperm concentration.
- High ambient temperature was linked to lower semen volume.
- High ambient temperature was linked to a lower total sperm count, but this was the least certain result of the six and it came close to showing no difference at all. It should not be read as being on the same footing as the others.
How to analyze the study yourself
- Study type
- Meta-analyses pool data from multiple studies to strengthen the signal, but they rely on the quality and consistency of the underlying studies.
- Population
- Men from Iran, Italy, Thailand, China, and Egypt.
- Funding
- Not reported
- Takeaway
- This study found that men working or living in sustained high heat had worse sperm on every measure the review looked at, with sperm shape and movement affected most. If you are trying to conceive and you work somewhere hot, it may be worth getting out of the heat where you can and keeping your testicles cool when you cannot.