Where a man lives shapes his sperm quality more than how he lives
A Spanish study of 386 men has revealed that geography — not personal habit — is the dominant force shaping male reproductive health, with men in northern Spain producing nearly twice the motile sperm of those in central regions. Lifestyle factors proved remarkably uniform across all areas studied, leaving researchers to look beyond individual behavior toward the invisible architecture of the environment: the air, the chemicals, the industrial residue of modern life. Presented at Europe's leading reproductive medicine conference, the findings reframe fertility not as a private matter of discipline, but as a public matter of policy — a question of what societies permit to drift through the air and seep into the body.
- Men in northern Spain produced nearly double the motile sperm of those in central Spain — a gap of 45 million cells that no amount of lifestyle adjustment could account for.
- Asthenozoospermia, a condition of impaired sperm movement, struck fewer than one in four northern men but more than half of those in southern and central regions, revealing a reproductive fault line drawn by place, not choice.
- When researchers stripped away every measurable lifestyle variable — smoking, drinking, weight, exercise — geography stubbornly remained the single strongest predictor of sperm quality.
- Scientists now point to air pollution, industrial chemicals, and plastic-derived compounds as the likely culprits, forces that individuals cannot neutralize through personal behavior alone.
- Researchers and reproductive health leaders are calling for larger environmental studies and stronger regulatory action, arguing that protecting fertility in future generations is a political responsibility, not a personal one.
A study presented at the European Society of Human Reproduction and Embryology's annual conference has uncovered a sharp geographic divide in male fertility across Spain — one that lifestyle choices cannot explain. Tracking 386 men at seven fertility clinics between mid-2024 and late 2025, researchers found that where a man lives predicts the quality of his sperm far more powerfully than how he lives.
The numbers were stark. Men in northern Spain averaged 94.35 million total motile sperm, compared with just 50.11 million in central Spain. Northern men also showed higher sperm concentration and better motility rates, while conditions like poor sperm movement and abnormal sperm shape were far more common in southern and central regions. Yet when researchers examined smoking rates, alcohol use, physical activity, and body weight across all regions, the groups looked nearly identical. Even after adjusting statistically for every measured personal factor, geography remained the dominant variable. Only abstinence duration before sample collection came close to mattering.
Lead researcher Professor Rocío Núñez-Calonge described the pattern as both striking and difficult to explain through conventional thinking. The most plausible interpretation, she argued, is environmental: air pollution, industrial chemicals, and plastic-derived compounds that individuals have no power to avoid through personal discipline. The north of Spain may simply carry a lighter burden of such exposures.
The finding resonates beyond Spain's borders. Similar regional patterns have been documented in other countries, suggesting a broader global dynamic in which environmental contamination quietly shapes reproductive outcomes. Núñez-Calonge called for larger studies and stronger public health regulations — framing pollution control as a fertility issue. Karen Sermon, immediate past chair of ESHRE, reinforced the message: while personal habits matter, the environmental forces now implicated in reproductive decline demand a response from national and European regulators, not just from individual men.
Researchers studying male fertility across Spain have uncovered a striking pattern: where a man lives appears to shape the quality of his sperm in ways that have nothing to do with how he lives. The finding, presented this week at the European Society of Human Reproduction and Embryology's annual conference, challenges the assumption that reproductive health is primarily a matter of personal choice.
The study tracked 386 men seeking fertility assessment at seven clinics across Spain between mid-2024 and the end of 2025. All participants answered detailed questionnaires about their habits—smoking, drinking, exercise, weight, medication, chemical exposure, drug use, caffeine intake. The researchers then sorted the men by region: north, south, southeast, and central Spain. What emerged was a clear geographic divide in semen quality that lifestyle factors simply could not explain.
Men in the north produced nearly twice as many motile sperm as those in central Spain. The average total motile sperm count in the north was 94.35 million, compared with 50.11 million in the center—a gap of almost 45 million cells. Northern men also showed higher sperm concentration (80.96 million per milliliter) and better motility rates (44.79%). Problems with sperm motility—a condition called asthenozoospermia—affected less than a quarter of northern men but struck more than half of those in the south and central regions. Abnormal sperm shape followed a similar geographic pattern.
Yet when researchers examined the lifestyle data, the regions looked remarkably alike. Smoking rates, alcohol consumption, physical activity, body weight, medical histories—all were broadly comparable. Even after statistically adjusting for every measured lifestyle and demographic factor, geography remained the strongest predictor of sperm quality. Only one other variable mattered: how long a man had abstained from sex before providing a sample. Everything else fell away.
Professor Rocío Núñez-Calonge, who led the research, described the finding as both striking and puzzling. The consistency of strong semen quality in the north, paired with the similarity of habits everywhere, pointed toward a different culprit: the environment itself. Air pollution, industrial chemicals, plastic compounds—invisible exposures that individuals cannot control through personal behavior. The north may simply have cleaner air or less industrial contamination than other regions.
The implications extend beyond Spain. Studies from multiple countries have documented similar regional variations in sperm quality, particularly in areas with diverse environmental conditions. If pollution and chemical exposure are indeed the drivers, the problem is not one that individual men can solve through better habits. It becomes a public health issue requiring policy intervention.
Núñez-Calonge called for larger, more rigorous studies to clarify the link between environmental exposure and reproductive health. She also urged stronger regulations to reduce air pollution, industrial chemicals, and plastic-derived compounds—framing pollution control as a matter of protecting fertility in future generations. Karen Sermon, the immediate past chair of ESHRE, echoed the point: while personal lifestyle clearly matters for sperm quality, environmental factors beyond individual control demand societal and political response. The responsibility, she suggested, lies with national and European regulators to act.
Citações Notáveis
If lifestyle habits were similar across regions, the differences in sperm quality likely stem from environmental exposures such as pollution or industrial contaminants rather than personal behavior.— Professor Rocío Núñez-Calonge, lead researcher
Environmental factors beyond individual control demand response at societal and political levels, with clear responsibility for national and EU regulators.— Professor Karen Sermon, Immediate Past Chair of ESHRE
A Conversa do Hearth Outra perspectiva sobre a história
So the study found that northern Spain has better sperm quality than other regions. But the men there don't live differently—they smoke the same, exercise the same, eat the same. What does that actually tell us?
It tells us that something in the air or water or soil is mattering more than anything a man chooses to do. If lifestyle was the answer, we'd see the north doing something visibly different. They're not. So the geography itself—the environment—must be doing the work.
But couldn't there be unmeasured lifestyle differences? Things the questionnaire didn't catch?
Possibly. But the researchers controlled for a lot—smoking, drinking, exercise, weight, medication, chemical exposure. At some point, if you've measured that much and geography still dominates, you have to ask what's in the environment that you're not measuring. Pollution. Industrial sites. Groundwater quality.
Why would northern Spain be different? Is it just cleaner?
That's the question no one can answer yet from this study alone. The north could have less industry, better air quality, different water sources. Or it could be something about how the regions developed. But the researchers are saying: stop assuming men's fertility is about their choices. Look at where they live.
And if this is true in Spain, it's probably true elsewhere?
Almost certainly. Other countries have seen the same regional patterns. If pollution is the driver in Spain, it's likely driving differences in Italy, Poland, anywhere with industrial variation. That's why the researchers are calling for policy change, not just more studies.
So what changes?
Regulations on air quality, industrial emissions, chemical use. The kind of thing that takes years and political will. But if you care about male fertility—and by extension, population health—you can't ignore that where someone lives might matter more than how they live.