Professor Mark Baker and his team at the University of Newcastle are building on earlier research with new technology to show how lowering testicular temperature could boost sperm quality and fertility outcomes.
When couples struggle to conceive, most people immediately think about treatments such as in vitro fertilisation (IVF), hormone injections, or egg retrieval, which center around the female partner. But new research suggests a surprising and much simpler solution might lie with men: keeping things cool. According to Professor Baker, the early signs are encouraging, and the approach could give couples new hope in their fertility journey.
Why Look at Cooling in the First Place?
Male infertility affects about 1 in 20 men worldwide1 and plays a role in nearly half of all couples struggling to conceive. Yet the treatments available overwhelmingly target women, even when the problem is clearly male-only.
“Assisted conception, such as IVF, can be invasive, costly, and emotionally draining, with no guaranteed success. Hence, our team asked a simple but neglected question: What if we directly treated men?” Professor Baker explains.
Hyperthermia (increased scrotal temperature) has long been known to reduce both semen output and quality in men.
How Heat Affects Sperm
Sperm production is extremely sensitive to heat. The testes need to be a few degrees cooler than body temperature, around 34°C. Even small increases above this level can damage sperm production.
Lifestyle contributes to the heat; for instance, spending long hours sitting, using laptops on your lap, wearing very tight clothing, or spending time in saunas or hot tubs may all contribute to heat stress in the testes.
“Our work and others’ show that heat not only reduces sperm count, motility, and normal shape but also increases DNA damage in sperm. This DNA damage can lead to embryo loss and failed pregnancies,” Professor Baker notes.
Cooling reverses this stress, lowers sperm DNA damage, and improves semen quality. Men may then have the option to attempt natural conception or pursue IVF rather than the more invasive ICSI. The catch? Improvements typically take 4–8 weeks to appear.
A Modern Take on an Old Idea
The idea of scrotal cooling is not new. According to Prof Baker, studies dating back to the 1980s2 suggested it might improve semen quality and even natural pregnancy rates. But early devices were impractical, bulky, uncomfortable, and not suited for daily life.
Professor Baker’s team decided to revisit the concept using modern engineering. They designed a wearable, discreet cooling device that men can comfortably use throughout their day.
In pilot studies, the results were dramatic:
- Sperm counts, movement, and shape all improved significantly.
- Men’s sperm quality shifted from well below average to about the middle of the normal range.
- DNA damage in sperm decreased dramatically.
For some men, these improvements meant moving out of the “infertile” range entirely, giving them the same chance of conception as most couples.
A Different Approach to Fertility
What makes this research unique is that it does not just test sperm and move straight to IVF or ICSI when the results are poor. Instead, it tries to treat the root cause in the male partner.
“Instead of bypassing the issue by injecting a single sperm into an egg, scrotal cooling aims to improve overall sperm health, numbers, and DNA quality, giving couples a chance at natural conception or improving outcomes if IVF is still needed,” he says.
What Couples Should Know About Male Fertility
One of the key messages from Professor Baker’s work is that fertility is not just a female issue. Male factors account for about half of infertility cases. Yet the burden of treatment — physical, financial, and emotional —falls disproportionately on women.
“Many men are surprised to learn that lifestyle, heat, and other factors can directly affect their sperm health. The hopeful message is that sperm quality can be improved, and men have a vital role in the fertility journey,” he says.
Looking Ahead
Professor Baker and his team see scrotal cooling as a potential low-cost, non-invasive option for couples trying to conceive. If larger clinical trials confirm the early findings, this simple approach could:
- Reduce the number of IVF cycles couples need to go through.
- Save families money and emotional stress.
- Improve chances of natural conception.
“In the long run, this research shifts the conversation: fertility treatment shouldn’t fall solely on women. Treating men directly, with something as simple and practical as cooling, we may finally achieve a more balanced and effective approach to fertility,’ he adds.
