If you’re trying to conceive – naturally or with ART support – here’s the simple truth: men’s health is half the story. In around 50% of infertility cases, a male factor is the main cause or part of the picture. That means there’s a lot men can do – starting today. [1]
Why talk about it now?
Because men’s sperm health and fertility has been sliding for decades. A major global review found average sperm concentration has dropped from roughly ~100 million/mL in the 1970s to ~50 million/mL by 2018, and the decline sped up after 2000. If that pace continued, straight-line projections nudge averages toward ~20 million/mL by mid-century. It’s a clear call to act. [2]
The heat piece
Testes work best when they run about 2-5 °C cooler than your core body temperature – that’s one reason they sit outside the body. When they overheat, the tiny “factories” inside slow down: testosterone output drops and new sperm production dips. Heat can also damage sperm already made, raising DNA fragmentation (tiny breaks in sperm DNA), so more sperm break down and get cleared. In short, heat is both a production and a quality problem. [3]
This isn’t just lab data. In human monitoring, scrotal temperature can rise by about ~3 °C in ~20 minutes on a conventional cushioned office chair. What does that mean? As a rule of thumb, each +1 °C rise is associated with roughly a 14% drop in sperm production; sustained +2–3 °C exposures in controlled human heating studies have driven counts down to contraceptive levels (and in some protocols, even temporary azoospermia). Repeated daily spikes matter. [4–6]
Clothing choices (yes, fabric matters)
Studies – including human textile-contact experiments – report that polyester against the scrotum can damage sperm cells: lower motility, more abnormal forms, and degenerative changes. The likely culprits are electrostatic effects and poorer cooling. Heat-stress studies in humans also show higher DNA fragmentation, meaning damaged sperm are more likely to break down and be cleared. The practical takeaway: prioritise breathability, airflow and smart design. [5–6]
Beyond conception: miscarriage risk & children’s health
This isn’t only about getting pregnant. Sperm quality matters for staying pregnant and for a child’s long-term health.
Miscarriage: Higher sperm DNA fragmentation is associated with increased miscarriage risk (including recurrent pregnancy loss in several analyses). Improving the testicular environment helps support better DNA integrity. [7–8]
Care pathways: IVF use is steadily rising; for example, ANZARD reported a 2.2% year-on-year increase in cycles from 2017 to 2018, with larger jumps in subsequent years. Wherever you are on the journey – natural or ART – male steps still matter. [9]
Quick definitions
Spermatogenesis → your sperm-making process. It runs like a production line that takes about ~74 days, plus a bit of transit time. Changes you make now usually show up in semen tests months, not days, later. [3]
Low testosterone (hypogonadism) → not enough testosterone from the testes. Common clues: low energy, low libido, mood shifts. A clinician needs to check and guide care.
Varicocele → enlarged scrotal veins. They can trap heat and reduce natural cooling; in selected men, repair has been linked with improvements (including testosterone). [3]
Where underwear design fits (and where Cool Beans helps)
Because position and airflow change the micro-climate, what you wear matters. Cool Beans is a TGA-registered testicular-cooling and support underwear designed to hold the scrotum gently forward – reducing thigh insulation and helping heat and sweat escape in everyday life. It’s not a cure or a replacement for medical care – it’s a practical, anatomy-aware base layer that plays nicely with nutrition, sleep, movement and clinician advice. Many men feel more comfortable within a week of reducing daily heat exposure. For bigger shifts in sperm health, think 3-4 months – long enough to influence the whole sperm lifecycle, plus a little buffer to get your body into a good rhythm.
(If this resonates, my book Cool Beans shares the science, stories and simple steps behind these changes-without the jargon stemming from my own infertility journey and how Cool Beans came to be.)
Four simple wins men can start this week
Cool: Break up sitting every 30–45 minutes; avoid pressing the scrotum against the thighs; choose breathable fabrics; pause long hot baths/saunas while trying to conceive. [4–6]
Nourish: Base meals on whole foods—plants, good fats, adequate protein. Less alcohol and no smoking lower oxidative stress that can harm sperm.
Rest: Guard your sleep—solid sleep patterns support hormone balance, including testosterone.
Unwind: Short, regular stress “down-shifts” (a walk, some breaths, a quick lift, a bit of sunlight) add up over weeks.
When to see a clinician
If trying is taking longer than expected—or you notice a heavy/veiny feel in the scrotum, or persistent low energy/libido—book in with a qualified clinician. Ask about semen analysis timing, a check for varicocele, and broader health screens that influence fertility and hormones. [3]
References (numbered, in-text)
Lifestyle & fertility overview noting male factor ≈ 50%: Reprod Biol Endocrinol, 2018.
Levine H. et al., Human Reproduction Update, 2023/2022 (global sperm decline; faster post-2000).
Testicular thermoregulation reviews; spermatogenesis ≈ 74 days; 2–5 °C cooler: RBMO 2014; Int J Mol Sci 2024.
Human scrotal-temperature monitoring on chairs (~+3 °C in ~20 min): Koskelo R. et al., 2005.
Rule-of-thumb heat impact (≈ 14% per +1 °C); human heating studies showing strong suppression at +2–3 °C: Springer chapter on testicular heat stress (2013/2014); Mieusset/Bujan human thermal-contraception studies.
Polyester/contact evidence and human heat-stress studies affecting sperm/DNA integrity: Shafik A., Andrologia/Contraception 1992; human sauna/hyperthermia papers (Andrology/Hum Reprod).
Sperm DNA fragmentation (SDF) associated with miscarriage: Human Reproduction meta-analysis, 2012.
SDF & recurrent pregnancy loss: Fertility & Sterility meta-analysis, 2019 (plus subsequent updates).
ANZARD (Australia & NZ IVF registry) report: cycles +2.2% from 2017→2018; broader trend upward.
