Over the last fifty years, a marked decrease in sperm count has been observed in the western world. But what about the situation in Switzerland? Up to now, no study had evaluated the reproductive health of Swiss young men. Researchers from the University of Geneva (UNIGE), Switzerland, working in collaboration with other institutions and with a logistical support from the Swiss army, have undertaken the first nationwide assessment of the semen quality of men between the age of 18 and 22. The scientists assessed three important parameters: the number of spermatozoa, their motility and morphology.
The results were well below the reference values issued by the World Health Organisation (WHO). The current situation is a matter of concern since the poor semen quality of Swiss men is associated with an increase in the incidence of testicular cancer.
The number of infertile couples in Switzerland using assisted reproductive technology (ART) doubled from 3,000 to over 6,000 a year between 2002 and 2010. Causes can be due to men as well as to woman, however in 10-15% of the cases, infertility is unexplained. Several environmental and lifestyle factors can influence the couple's fertility stress, alcohol or cigarette consumption to list a few. A determining factor in a men's fertility is his semen quality.
Numerous epidemiological studies in industrialised countries over the past decades have shown a drop in semen quality with a particular decrease in the sperm concentration from 99m per ml to 47m per ml. "It's important to understand that the time needed to conceive increase significantly if a man has a sperm concentration below 40m sperm per ml," explains Dr Serge Nef, professor in the department of genetic medicine and development in UNIGE's faculty of medicine. A man whose sperm concentration is below 15m per ml can be considered sub-fertile and is more likely to encounter problems conceiving a child, regardless of the fertility of his partner. Infertility is defined as the inability to conceive after 12 months of regular unprotected sexual intercourse.
The UNIGE researchers conducted the first national study on the quality of Swiss sperm by analysing the profile of 2,523 young men aged 18 to 22 as part of their military recruitment. The men came from every canton in Switzerland and were conceived and born in the country. They completed a questionnaire about their health, lifestyle, diet and education. In addition, their parents filled in a questionnaire about their own lifestyle, diet, health and the course of the pregnancy. This was designed to assess the conditions under which gestation took place and to evaluate the possible impact on the reproductive health of the young men. Semen quality is defined by three important parameters: the sperm concentration (number of sperm per ml), their motility and morphology. "Low semen parameters values can reflect a men's fertility, when a combination of values are low, a men's ability to conceive is at risk," says Rita Rahban, a researcher in the department of genetic medicine and development and the study's first author.
The researchers analysed the semen samples of the volunteers by measuring the semen volume and the sperm concentration, motility and morphology.
Sperm counts vary from one country to another, with median concentrations ranging between 41m to 67m per ml for young European men. By way of comparison, Swiss men with 47m per ml are at the bottom of the pack alongside Denmark, Norway and Germany.
Based on the WHO thresholds established in 2010, the results of the study indicate that 17% of young men had a sperm concentration below 15m per ml and 25% had less than 40% motile spermatozoa in their ejaculate. The rate of morphologically normal forms was below 4% in 40% of the subjects. The study as a whole revealed that at least one of the three parameters (concentration, motility and morphology) was below the WHO thresholds for 60% of men, and that 5% had a problem concerning these three factors at the same time. "We need to be cautious about a single semen analysis," points out Dr Alfred Senn, an andrologist and co-author of the study. "It isn't entirely predictive of a person's fertility. But, in overall terms, the results suggest that the sperm quality of young men in Switzerland is in a critical state and that their future fertility will in all likelihood be affected."
The study did not identify differences in sperm quality between Switzerland's various geographical regions, linguistic areas, as a proxy for different lifestyle factors. There were also no differences between urban or rural regions. However, maternal smoking during pregnancy was found to be associated with a decrease in sperm quality, as Nef adds: "Subfertility was found to be more common among men who were exposed to maternal smoking during embryonic development."
The Geneva-based researchers also used the study to identify a correlation between poor semen quality and increased testicular cancer in Switzerland. "For 35 years, testicular cancer has grown steadily to over 10 cases per 100,000 men, which is very high compared to other European countries. Sperm quality is generally lower in countries where the incidence of testicular cancer is high," says Nef. This is almost certainly the result of altered testicular development at the foetal stage, prompting the scientists to further investigate this area.
The UNIGE researchers are now working to identify the causes by further assessing the impact of environmental or lifestyle factors. "We would also like to go back to the 2,523 men who took part in the study in about 10 years so we can follow up their reproductive health and find out whether they have had children or have suffered from testicular cancer, for example," continues Rahban. "With the current trend for couples to have children later in life, the low sperm count among young men in Switzerland – combined with the declining fertility of older women – will have an impact on conception rates and future generations. This will lead to significant social and financial challenges for our society," concludes Senn.
The study is the end result of a partnership of over 15 years involving numerous stakeholders, who have often been volunteers. Their number includes researchers from UNIGE, Denmark and France; the FABER Foundation that initiated this study and various andrology centres throughout Switzerland; the National Institute for Cancer Epidemiology and Registration (NICER); logistical support from the Swiss Army; the Swiss Centre for Applied Human Toxicology (SCAHT); the HUG Foundation in Geneva; and the Swiss National Science Foundation (PNR50).
Abstract
Background: Sperm counts have been steadily decreasing over the past five decades with regional differences in the Western world. The reasons behind these trends are complex, but numerous insights indicate that environmental and lifestyle factors are important players.
Objective: To evaluate semen quality and male reproductive health in Switzerland.
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.
Authors
R Rahban, L Priskorn, A Senn, E Stettler, F Galli, J Vargas, M van den Bergh, A Fusconi, R Garlantezec, TK Jensen, L Multigner,NE Skakkebæk, M Germond, N Jørgensen, S Nef
[link url="https://www.eurekalert.org/pub_releases/2019-05/udg-psq052019.php"]University of Geneva material[/link]
[link url="https://onlinelibrary.wiley.com/doi/full/10.1111/andr.12645"]Andrology abstract[/link]