About 1 in 6 people worldwide (17.5%) experience infertility at some point in their lives, according to the World Health Organization's 2023 analysis of 133 studies. A male factor is found in about half of couples who can't conceive and is the only cause in about 20%, according to the European Association of Urology. An estimated 56.5 million men were living with infertility in 2019 (Global Burden of Disease estimate, with a wide range of 32 to 90 million). The largest meta-analysis of sperm counts found sperm concentration fell by 51.6% between 1973 and 2018 in men not selected for fertility, though a 2024 analysis of American men found no clinically significant decline and the trend is still debated. The WHO's 2021 lower reference limit for sperm concentration is 16 million per mL.
The headline numbers
| Statistic | Figure | Source |
|---|---|---|
| People who experience infertility in their lifetime | 17.5% (about 1 in 6) | WHO, 2023 |
| People with infertility in any 12-month period | 12.6% | Cox et al., 2022 (WHO analysis) |
| UK couples who may have difficulty conceiving | Around 1 in 7 | NHS |
| Infertile couples where a male factor is found | About 50% | EAU guidelines, 2026 |
| Infertile couples where the male factor is the only cause | About 20% | EAU 2026; AUA/ASRM 2024 |
| Men living with infertility worldwide (2019) | About 56.5 million (range 32 to 90 million) | Huang et al., 2023 (GBD 2019) |
| Fall in sperm concentration, 1973 to 2018 | 51.6% (disputed) | Levine et al., 2023 |
| Men with no sperm in the ejaculate (azoospermia) | About 1% of all men; about 15% of infertile men | AUA, 2010 |
| Men with a varicocele | About 15% of men; 35 to 40% of men with infertility | EAU guidelines, 2026 |
| Couples who conceive within a year (woman under 40) | Over 80%; over 90% within two years | NICE NG257 |
| Men evaluated for infertility found to have a serious undiagnosed condition | 1 to 6% | AUA/ASRM, 2024 |
| WHO 2021 lower reference limit for sperm concentration | 16 million per mL | WHO, 2021 |
How common is infertility?
The WHO's 2023 report pooled 133 studies from every region, covering 1990 to 2021, and found a lifetime prevalence of 17.5%: roughly 1 in 6 adults experience infertility at some point. The figure was similar in high-income countries (17.8%) and in low- and middle-income countries (16.5%). In any given 12-month period the figure was 12.6%. Infertility here uses the standard clinical definition: no pregnancy after 12 months or more of regular unprotected sex.
Two details matter when you quote this. The 17.5% counts people over a lifetime, not couples at one moment, so "1 in 6 couples are infertile right now" overstates it. And most people who meet the 12-month definition still conceive later. The UK's NICE guideline says over 80% of couples conceive within a year when the woman is under 40, about half of the rest conceive in the second year, and the cumulative rate passes 90% by two years. The NHS puts the UK figure at around 1 in 7 couples having difficulty conceiving, and the European Association of Urology says about 15% of couples don't conceive within 12 months and seek treatment.
How often is it the man?
About half the time the man is part of the picture. The European Association of Urology's 2026 guideline says a male-infertility-associated factor is found in 50% of involuntarily childless couples, and a purely male factor in about 20%. The joint American Urological Association and American Society for Reproductive Medicine guideline (2020, amended 2024) gives the same shape: a male factor is solely responsible in about 20% of infertile couples and contributes in another 30 to 40%. A widely cited 2015 review puts male factors alone at 20 to 30% of cases, and says male factors contribute to about 50% of cases overall.
Up to about 25% of couples end up with unexplained infertility, where standard tests find nothing on either side. That is one reason a man's semen analysis is part of the first round of tests in UK guidance rather than an afterthought.
There is a health reason too. The AUA/ASRM guideline notes that 1 to 6% of men evaluated for infertility turn out to have a significant undiagnosed medical condition, including cancers. A semen analysis can be the first test that sends a man to a doctor.
How many men have infertility worldwide?
A 2023 analysis of Global Burden of Disease data estimated about 56.5 million men were living with infertility in 2019, up 76.9% from about 32 million in 1990. Much of that rise reflects population growth: the age-standardized prevalence rose 19%, to about 1,403 per 100,000 men. The uncertainty is large (the 95% range runs from about 32 million to 90 million), because most countries don't collect male infertility data at all. An older, frequently quoted estimate from the 2015 review is "at least 30 million men".
Is sperm count falling?
Two large meta-regressions by Hagai Levine and colleagues say yes. The 2017 analysis of 185 studies and 42,935 men found that, among men from North America, Europe, Australia and New Zealand who were not selected for fertility, sperm concentration fell 52.4% between 1973 and 2011 (1.4% a year) and total sperm count fell 59.3%. The 2023 update, 223 studies and 57,168 men across all continents, found concentration fell 51.6% between 1973 and 2018 among men not selected for fertility, and total count fell 62.3%, with the yearly decline steepening from 1.16% across the whole period to 2.64% a year after 2000.
Not everyone accepts the trend. These analyses combine decades of published studies that used different counting methods and recruited different kinds of men, and the authors themselves say the cause is unknown. A 2024 meta-analysis of 75 study populations covering 11,787 American men from 1970 to 2018 concluded there was "no clinically significant decline in sperm concentration" among fertile men and the general US population. A fair summary: the global decline is the stronger and larger body of evidence, the size and cause of it are genuinely contested, and no one should quote it as a collapse.
Specific conditions
- Azoospermia (no sperm in the ejaculate): present in about 1% of all men and approximately 15% of infertile men, according to the AUA.
- Varicocele (enlarged veins in the scrotum): present in almost 15% of men in general, 25% of men with an abnormal semen analysis and 35 to 40% of men presenting with infertility, according to the EAU guideline.
- Unexplained infertility: up to about 25% of couples, per AUA/ASRM.
The lifestyle numbers with the strongest evidence
Most of these are observational, so they show association rather than proof of cause. They are the best-quality figures available for each factor.
- Smoking. A 2016 meta-analysis of 20 studies and 5,865 men found smokers had a sperm concentration 9.7 million per mL lower, motility 3.5 percentage points lower and normal morphology 1.4 points lower than non-smokers, with bigger gaps in moderate and heavy smokers. More in the smoking and vaping guide.
- Weight. A 2013 meta-analysis of 21 studies and 13,077 men found the odds of a low sperm count or no sperm were 1.11 times higher in overweight men, 1.28 times higher in obese men and 2.04 times higher in men with a BMI of 40 or more. More in the weight guide.
- Age. A 2015 meta-analysis of 90 studies and 93,839 men found semen volume, motility, progressive motility, normal morphology and DNA integrity all declined with age. Sperm concentration, unexpectedly, did not. More in the age guide.
- Testosterone therapy. In a WHO contraceptive trial of 271 men given weekly testosterone injections, about 65% had no sperm at all within six months. Every major urology guideline advises against testosterone for men trying to conceive. More in the testosterone guide.
The WHO 2021 reference limits
The WHO's 2021 semen manual sets its lower reference limits at the 5th centile of more than 3,500 men from twelve countries on five continents whose partners conceived within a year. By design, 95% of that reference group sit above these numbers, and a result below one of them is a reason to retest and investigate, not a diagnosis. The data paper that set them says plainly that the limits "do not represent distinct limits between fertile and subfertile men".
| Measure | WHO 2021 lower reference limit |
|---|---|
| Semen volume | 1.4 mL |
| Sperm concentration | 16 million per mL |
| Total sperm count | 39 million per ejaculate |
| Total motility | 42% |
| Progressive motility | 30% |
| Normal morphology | 4% |
| Vitality | 54% |
The semen analysis guide explains each line, and the semen analysis checker compares your own numbers with these limits.
How long it takes to make sperm
Sperm production takes roughly two to two and a half months. Heller and Clermont's tracer studies put spermatogenesis at about 64 days in 1963 and revised it to about 74 days in 1964, which became the textbook figure. A 2006 study that labeled new cells with heavy water found them in the ejaculate after an average of 64 days, with a range of 42 to 76 days. That is why clinics repeat an abnormal semen analysis about three months later, and why the how-long guide says any change needs two to three months to show.
What men know about their own fertility
Not much, on average. In a 2016 survey of 701 Canadian men aged 18 to 50, men correctly identified 51% of the risk factors and 45% of the health issues linked to male infertility. Fewer than a third knew that frequent cycling (27.5%), heavy use of electronic devices (26.0%) or hot tub use (33.0%) could be risk factors, and 35.8% said they had at least some concerns about their fertility.
Fertility treatment in the UK
The Human Fertilisation and Embryology Authority's latest figures, for 2024 and published in June 2026, show about 64,000 patients had more than 100,000 treatment and freezing cycles at licensed UK clinics, around 53,000 of them having IVF. The NHS funded 28% of IVF cycles in 2024, down from 35% in 2019. The HFEA's trends report doesn't break out male-factor cases, but an analysis of the HFEA register from 2005 to 2018 found about half of the first fresh IVF and ICSI cycles it analyzed used ICSI (injecting a single sperm into the egg), and 90% of cycles with male factor infertility did.
Using these figures
You're welcome to quote any number on this page. Please link to this page or, better, to the primary source in the list below, and keep the caveats that travel with the number (the 1 in 6 is lifetime prevalence, and the sperm count decline is disputed). We re-check every figure at least once a quarter and date the page when anything changes. If you spot an error, email hello@motily.app and we'll correct it and say so, as the editorial policy promises.
Common questions
What percentage of infertility is male factor?
A male factor is found in about half of infertile couples and is the only cause in about 20%, according to the European Association of Urology and the AUA/ASRM guideline. Some reviews put the male-only share as high as 30%.
Is it true that sperm counts have halved?
The largest meta-analysis found sperm concentration fell 51.6% between 1973 and 2018 in men not selected for fertility, using data from 57,168 men. It is disputed: the studies it combines used different methods over five decades, and a 2024 analysis of American men found no clinically significant decline. Treat it as a strong signal with an uncertain size, not a settled fact.
What is a normal sperm count?
The WHO's 2021 lower reference limits are a concentration of 16 million per mL and a total of 39 million per ejaculate. These are the 5th centile of fertile men, so most fertile men are well above them, and a number below them calls for a repeat test rather than a conclusion.
How many men are infertile?
About 56.5 million men worldwide in 2019, by a Global Burden of Disease estimate, with an uncertainty range of roughly 32 to 90 million because most countries don't measure it.
Related guides
Sources
- World Health Organization. 1 in 6 people globally affected by infertility (Infertility prevalence estimates, 1990 to 2021). 2023.
- Cox CM, et al. Infertility prevalence and the methods of estimation from 1990 to 2021: a systematic review and meta-analysis. Human Reproduction Open, 2022.
- NHS. Infertility.
- National Institute for Health and Care Excellence. Fertility problems: assessment and treatment (NG257). 2026.
- European Association of Urology. Guidelines on Sexual and Reproductive Health: male infertility. 2026.
- American Urological Association and American Society for Reproductive Medicine. Diagnosis and treatment of infertility in men: AUA/ASRM guideline. 2020, amended 2024.
- Agarwal A, et al. A unique view on male infertility around the globe. Reproductive Biology and Endocrinology, 2015.
- Huang B, et al. Global, regional and national burden of male infertility in 204 countries and territories between 1990 and 2019: an analysis of global burden of disease study. BMC Public Health, 2023.
- Levine H, et al. Temporal trends in sperm count: a systematic review and meta-regression analysis. Human Reproduction Update, 2017.
- Levine H, et al. 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, 2023.
- Lewis K, et al. Sperm concentration remains stable among fertile American men: a systematic review and meta-analysis. Fertility and Sterility, 2025 (online 2024).
- American Urological Association. The evaluation of the azoospermic male: AUA best practice statement. 2010, revised 2011.
- Sharma R, et al. Cigarette smoking and semen quality: a new meta-analysis examining the effect of the 2010 World Health Organization laboratory methods for the examination of human semen. European Urology, 2016.
- Sermondade N, et al. BMI in relation to sperm count: an updated systematic review and collaborative meta-analysis. Human Reproduction Update, 2013.
- Johnson SL, et al. Consistent age-dependent declines in human semen quality: a systematic review and meta-analysis. Ageing Research Reviews, 2015.
- World Health Organization Task Force on Methods for the Regulation of Male Fertility. Contraceptive efficacy of testosterone-induced azoospermia in normal men. The Lancet, 1990.
- World Health Organization. WHO laboratory manual for the examination and processing of human semen, sixth edition. 2021.
- Campbell MJ, et al. Distribution of semen examination results 2020: a follow up of data collated for the WHO semen analysis manual 2010. Andrology, 2021.
- Heller CG, Clermont Y. Spermatogenesis in man: an estimate of its duration. Science, 1963.
- Heller CG, Clermont Y. Kinetics of the germinal epithelium in man. Recent Progress in Hormone Research, 1964.
- Misell LM, et al. A stable isotope-mass spectrometric method for measuring human spermatogenesis kinetics in vivo. Journal of Urology, 2006.
- Daumler D, et al. Men's knowledge of their own fertility: a population-based survey examining the awareness of factors that are associated with male infertility. Human Reproduction, 2016.
- Human Fertilisation and Embryology Authority. Fertility treatment 2024: trends and figures. 2026.
- Paffoni A, et al. Intracytoplasmic sperm injection versus conventional in vitro insemination in couples with non-male infertility factor in the "real-world" setting: analysis of the HFEA registry. Journal of Translational Medicine, 2024.
