Very Low Swiss Sperm Quality Underscores a Troubling Worldwide Trend 

Sperm counts around the world are in decline, but the severity of the issue varies by nation. In response, some countries are taking it upon themselves to determine just how dire their individual sperm situations are. The latest to add its woes to the list is Switzerland, which recently conducted a national-level study on semen quality that turned up some less-than-stellar results.

In a paper published in Andrology this week, University of Geneva scientist revealed that Swiss sperm quality falls near the bottom of the pack in Europe — and far short of World Health Organization standards.

Seventeen percent of young Swiss men in the sample group had sperm counts below WHO thresholds, 25 percent had sperm that fell short of WHO’s motility threshold, and 43 percent had a percentage of abnormal sperm (more than 4 percent) that placed them below WHO standards for fertility. Overall, only 38 percent of men surpassed the standards in each category. 

In response to the results, study author Alfred Senn, Ph.D., said that these results speak to the “critical state” of Swiss sperm. Rita Rahban, a doctoral candidate and the study’s first author, told Inverse that these results could have important implications for fertility in the future.

“From a public health perspective, our results suggest that an important amount of men will probably take more time to conceive and 5% will have most probably to seek medically assisted reproductive technologies,” Rahban says.

As bad as these results look for Switzerland, it turns out that their results are in good company in the western world, where declines in semen quality have researchers searching for answers.

The Bigger Picture

The United States, China, and more than one European country (see Denmark and France, for example) have also noted declines in sperm count and quality — though not all of the studies showing these results have been conducted on a national level, as Switzerland’s was. In 2017, a review in Human Reproduction Update took all that evidence into account to declare that sperm counts had declined between 50 and 60 percent in North America, Australia, New Zealand, and Europe between 1973 and 2011.

But what does it exactly mean to have declines in sperm quality? At least going by the World Health Organization’s updated international standards for semen quality, it means evaluating three things: sperm count, motility (swimming ability), and morphology (shape).

The WHO’s reference value for sperm count is about 15 million swimmers per milliliter of semen. Forty percent of those sperm have to be motile, and 4 percent must have relatively normal shapes. These are just guidelines that can be used to approximate “prospects for fertility,” and importantly, these are also the values that the study in Switzerland used to evaluate national sperm quality.

The results of this Swiss study add another puzzle piece to help prove that there truly is something up with sperm by taking samples of semen from 2,523 men between 18 and 22 who attended Swiss army clinics. That way, Rahban explains, they could be sure that they weren’t just sampling from fertility clinics, which could bias their data. This has been a concern about semen quality studies in the past.

“In general, there exist two types of populations in studies that aim at evaluating semen quality: One is fertile men consulting fertility clinics (that we think has an important potential selection bias) and studies on young men (recruited in the context of conscription) which we think to represent well the general population,” she says.

With those results in hand, the team can be fairly sure that there’s something going on with sperm quality in Switzerland. They’re not exactly sure what it is, but there are some circulating ideas.

Why Is Semen Quality Declining?

Rahban notes that maternal smoking was strongly associated with low semen quality in their sample, adding fuel to the idea that exposure to harmful agents during early development can take a toll on sperm later on. But that’s just one idea. There are plenty of things that happen during a man’s life that could impact sperm count, motility, or morphology.

"We think that environmental and lifestyle factors play an important role."

Generally, the idea is that many different factors might affect sperm quality, including exposure to pollution, obesity, stress, or smoking tobacco. Marijuana, on the other hand, has shown some counterintuitive effects on sperm count.

Rahbad makes it clear that there probably is no single cause (at least in Switzerland), but that ultimately, we’ll find that some combination of all these factors is behind declining sperm quality.

“What we know is that there is not only one reason why more than half of the investigated population has at least one value below the WHO reference values,” Rahban says. “There are probably many factors. We think that environmental and lifestyle factors play an important role.”

The results of Switzerland’s national-level inquiry into the health of the nation’s sperm may not have been as positive as Swiss citizens had hoped for. But the good news is that they aren’t alone — or even actually that far off from other places around the world. The state of Swiss sperm and the research around it might just push us one step closer to understanding why the declines are happening in the first place.

Partial Abstract:

Materials and Methods: A nationwide cross‐sectional study was conducted on 2523 young men coming from all regions of Switzerland, recruited during military conscription. Semen volume, sperm concentration, motility, and morphology were analyzed. Anatomy of the genital area and testicular volume was recorded. Testicular cancer incidence rates in the general population were retrieved from Swiss regional registries.

Results: Median sperm concentration adjusted for period of sexual abstinence was 48 million/mL. Comparing with the 5th percentile of the WHO reference values for fertile men, 17% of men had sperm concentration below 15 million/mL, 25% had less than 40% motile spermatozoa, and 43% had less than 4% normal forms. Disparities in semen quality among geographic regions, urbanization rates, and linguistic areas were limited. A larger proportion of men with poor semen quality had been exposed in utero to maternal smoking. Furthermore, testicular cancer incidence rates in the Swiss general population increased significantly between 1980 and 2014.

Discussion: For the first time, a systematic sampling among young men has confirmed that semen quality is affected on a national level. The median sperm concentration measured is among the lowest observed in Europe. No specific geographical differences could be identified. Further studies are needed to determine to what extent the fertility of Swiss men is compromised and to evaluate the impact of environmental and lifestyle factors.

Conclusion: A significant proportion of Swiss young men display suboptimal semen quality with only 38% having sperm concentration, motility, and morphology values that met WHO semen reference criteria.