Skip to main content

Baisse de la production et de la qualite spermatique chez l’homme: Facteurs de variation et problemes méthodologiques

Factors modulating human sperm production and quality and methodological bias of studies on semen quality

Resume

Plusieurs travaux rétrospectifs publiés récement indiquent des évolutions séculaires différentes et des variations géographiques de la qualité du sperme humain. La responsabilité possible de facteurs professionnels ou environnementaux a souvent été évoquée. La controverse suscitée par ces travaux est importante. Il est souvent avancé que les études publiées sont sans valeur du fait des biais de recrutement ou des biais méthodologiques qu’elles contiennent. Tous ces travaux confirment la très grande variabilité intra- et interindividuelle des caractéristiques du sperme. Différents facteurs comme l’âge des hommes ou le délai d’abstinence sexuelle avant le prélèvement influencent la concentration de spermatozoïdes mais ils n’expliquent qu’une faible partie de la variabilité qui dépend aussi d’autres facteurs encore non identifiés. L’étude des facteurs de variation de la qualité du sperme est complexe car elle n’est pas exempte de biais. Le premier des biais possibles concerne la méthodologie même d’analyse du sperme, qui se caractérise par sa forte subjectivité, notamment en l’absence de procédures parfaitement standardisées. D’autres biais possibles sont dûs à l’hétérogénéité ou à la taille des populations étudiées, ou encore à la méthodologie statistique utilisée. A côté des études portant sur le sperme humain sujettes à de nombreuses critiques, différentes données d’observation chez l’homme et dans la faune sauvage et de récents travaux expérimentaux indiquent que l’hypothèse d’une dégradation de la fonction de reproduction mâle doit être prise au sérieux. Pour progresser dans l’étude des modifications éventuelles de la production et de la qualité spermatique, il apparaît donc urgent de développer des études prospectives minimisant tous les biais possibles. Parallèlement, des études expérimentales visant à étudier les facteurs suspectés de modifier la fonction de reproduction mâle doivent être entreprises dans le but d’une connaissance de la physiopathologie des mécanismes en causes.

Abstract

In the last few years, the possible decline of human semen quality as well as the important geographical variations of semen quality have been discussed in several scientific articles. In a meta-analysis of 61 publications worldwide, Carlsen et al. found a trend of decreasing sperm count over the past 50 years. This work has been at the origin of many commentaries and controversy. Two kinds of questions were mainly raised: Is the phenomenon real? what could be the reason(s) for such a decline? Many sceptical attitudes facing the conclusions of Carlsen et al. came from the fact that the studies included in the meta-analysis were done in various countries at different times, that the men studied could be very heterogeneous in term of fertility status and that the sample sizes of many studies were very low. It was also advocated that the results could be influenced by cofactors as the man’s age or the duration of sexual abstinence before semen collection or by differences in the methodologies used to analyse the semen samples in the various centers. Interestingly, several retrospective studies from a single centre were published after the meta-analysis of Carlsen reporting data from different groups of men recruited during more than 10 years periods in the last decades. Some of these studies found a decline of sperm concentration while for others, no secular modification of sperm concentration could be observed. It was also noticed important differences between values of semen characteristics in these various studies raising the question of geographical or regional differences besides the secular trend observed. Most of the published studies were very imprecis or poor of information concerning the men included in the study, the technical conditions used for semen analysis, the statistical methods used and the interpretation of the data. We discuss here some of the data of these studies in the context of the actual debate on the modifications of semen quality with the aim to pin-point the methodological bias contributing to the variation in the evaluation of semen quality. Moreover we also discuss the current data on the factors related to the men and their environment which could modulate sperm production and quality. It is mandatory to determine if the man’s reproductive function is influenced by environmental factors and if yes how they act. May be one of the main interest of the ongoing debate will be to develop basic and prospective epidemiological research in the field.

References

  1. 1.

    ADAMANPOULOS D., PAPPA A., NICOPOULOU S., ANDREOU E., KARAMERTZANIS M., MICHOPOULOS J., DELIGIANNI V., SIMOU M.: Seminal volume and total sperm number trends in men attending subfertility clinics in the Greater Athens area during the period 1977–1993. Human Reprod., 1996, 11: 1936–1941.

    Google Scholar 

  2. 2.

    ADAMI H., BERGSTRÖM R., MÖHNER M., ZATONSKI W., STORM H., EKBOM A., TRETLI S., TEPPO L., ZIEGLER H., RAHU M., GUREVICIUS R., STENGREVICS A.: Testicular cancer in nine northern european countries. Int. J. Cancer, 1994, 59: 33–38.

    PubMed  Article  CAS  Google Scholar 

  3. 3.

    AUGER J., KUNSTMANN J.M., CZYGLIK F., JOUANNET P.: Decline in semen quality among fertile men in Paris during the past 20 years. New Engl. J. Med., 1995, 332: 281–285.

    PubMed  Article  CAS  Google Scholar 

  4. 4.

    BECKER S., BERHANE K.: A meta-analysis of 61 sperm count studies revisited. Fertil. Steril., 1997, 67: 1103–1108.

    PubMed  Article  CAS  Google Scholar 

  5. 5.

    BRAKE A., KRAUSE W.: Decreasing quality of semen (letter). Br. Med. J., 1992, 305: 1498.

    CAS  Google Scholar 

  6. 6.

    BROMWICH P., COHEN J., STEWART I., WALKER A.: Decline in sperm counts: an artefact of changed reference range of «normal»? Br. Med. J., 1994, 309: 19–22.

    CAS  Google Scholar 

  7. 7.

    BUJAN L., MANSAT A., PONTONNIER F., MIEUSSET R.: Sperm concentration in donor 1977–1992 in Toulouse, France. Br. Med. J., 1996, 312: 471–472.

    CAS  Google Scholar 

  8. 8.

    CARLSEN E., GIWERCMAN A., KEIDING N., SKAKKEBAEK N.E.: Evidence for decreasing quality of semen during past 50 years. Br. Med. J., 1992, 305: 609–613.

    CAS  Google Scholar 

  9. 9.

    CLAVERT A.: Le groupe de travail “Assurance de Qualité en Biologie de la Reproduction”. Andrologie, 1997, 7: 414–418.

    Google Scholar 

  10. 10.

    COOPER T.G., NEUWINGER J., BAHRS S., NIESCHLAG E.: Internal quality control of semen analysis. Fertil. Steril., 1992, 58: 172–178.

    PubMed  CAS  Google Scholar 

  11. 11.

    DE MOUZON J., THONNEAU P., SPIRA A., MULTIGNER L.: Semen quality has declined among men born in France since 1950. Br. Med. J., 1996, 313: 43.

    Google Scholar 

  12. 12.

    ELIASSON R.: Parameters of male fertility. In: Hafez ESE, Evans TN eds. Human Reproduction, Conception and Contraception. Hagerstown: Harper and Row, 1973 pp 39–51

    Google Scholar 

  13. 13.

    FARROWS S.: Falling sperm quality: fact or fiction? Br. Med. J., 1994, 309: 1–2.

    Google Scholar 

  14. 14.

    FÉDÉRATION CECOS, AUGER J., JOUANNET P.: Evidence for regional differences of semen quality among fertile french men. Human Reprod., 1997, 12: 740–745.

    Article  Google Scholar 

  15. 15.

    FISCH H., GOLUBOFF E.T.: Geographic variations in sperm counts: a potential bias in studies on semen quality. Fertil Steril, 1996, 65, 1044–1046

    PubMed  CAS  Google Scholar 

  16. 16.

    FISCH H., GOLUBOFF E.T., OLSON J.H., FELDSHUH J., BRODER S.J., BARAD D.H.: Semen analysis in 1283 men from the United States over a 25-year period: no decline in quality. Fertil. Steril., 1996, 65: 1009–1014.

    PubMed  CAS  Google Scholar 

  17. 17.

    FUKUDA M., FUKUDA K., TAKASHI S., YOMURA W., SHIMIZU T.: Kobe earthquake and reduced sperm motility. Human Reprod., 1996, 11: 1244–1246.

    CAS  Google Scholar 

  18. 18.

    GIBLIN P.T., POLAND M.L., MOGHISSI K.S., AGER J.W., OLSON J.M.: Effects of stress and characterisite adaptability on semen quality in healthy men. Fertil. Steril., 1988, 49: 127–132.

    PubMed  CAS  Google Scholar 

  19. 19.

    IRVINE D.S., CAWOOD E., RICHARDSON D., MACDONALD E., AITKEN J.: Evidence of deteriorating semen quality in the United Kingdom: birth cohort study of 577 men in Scotland over 11 years. Br. Med. J., 1996, 312: 467–470.

    CAS  Google Scholar 

  20. 20.

    JOUANNET P., AUGER J.: Declining sperm counts? More research is needed. Andrologia 1996, 28: 302–303.

    PubMed  CAS  Article  Google Scholar 

  21. 21.

    KEIDING N., GIWERCMAN A., CARLSEN E., SKAKKEBAEK N.E.: Importance of empirical evidence (commentary). Br. Med. J., 1994, 309: 22.

    Google Scholar 

  22. 22.

    LEVINE R.J.: Seasonal variation of semen quality and fertility. International Symposium on Environment, Lifestyle and Fertility, Aarhus, Danemark, 1997. Abstract book: 59–62.

  23. 23.

    LILFORD R., JONES A.M., BISHOP D.T., THORNTON J., MUELLER R.: Case-control study of whether sublfertility in men is familial. Br. Med. J., 1994, 309: 570–573.

    CAS  Google Scholar 

  24. 24.

    MACLEOD J., GOLD R.Z.: The male factor in fertility and infertility. VIII. A study of variation in semen quality. Fertil. Steril., 1956, 7: 387–410.

    PubMed  Google Scholar 

  25. 25.

    NELSON C.M.K., BUNGE R.G.: Semen analysis: Evidence for changing semen parameters of male fertility potential. Fertil. Steril., 1974, 25: 503–507.

    PubMed  CAS  Google Scholar 

  26. 26.

    OLSEN G.W., BODNER K.M., RAMLOW J.M., ROSS C.E., LIPSHULTZ L.I.: Have sperm counts been reduced 50% in 50 years? A statistical model revisited. Fertil. Steril., 1995, 63, 887–893.

    PubMed  CAS  Google Scholar 

  27. 27.

    PAULSEN C.A., BERMAN N.G., WANG C.: Data from men in greater Seattle area reveals no downward trend in semen quality: further evidence that deterioration of semen quality is not geographically uniform. Fertil. Steril. 1996, 65: 1015–1020.

    PubMed  CAS  Google Scholar 

  28. 28.

    SCHAFER D., ARREDONDO-SOBERON F., LORET DE MOLA J.R., BLASCO L.: Has sperm quality declined in the 1990’s: analysis from a donor program. 52nd Annual Meeting of the American Society for Reproductive Medicine, 1996, Abstract book: 286.

  29. 29.

    SCHWARTZ D., MAYAUX M.J., SPIRA A., MOSCATO M.L., JOUANNET P., CZYGLIK F., DAVID G.: Semen characteristics as a function of age in 833 fertile men. Fertil. Steril., 1983, 39: 530–535.

    PubMed  CAS  Google Scholar 

  30. 30.

    TOPPARI J., LARSEN J.C., CHRISTIANSEN P. et al.: Male reproductive health and environmental xenoestrogens. Environ. Health Perspect., 1996, 104, Suppl. 4, 741

    PubMed  Article  CAS  Google Scholar 

  31. 31.

    TUMON I.S., MORTIMER D.: Decreasing quality of semen (letter). Br. Med. J., 1992, 305: 1228–1229.

    Article  Google Scholar 

  32. 32.

    VAN WAELEGHEM K., DE CLERCQ N., VERMEULEN F., SCHOONJANS F., COMHAIRE F.: Deterioration of sperm quality in young healthy belgian men. Human Reprod., 1996, 11: 325–329.

    Google Scholar 

  33. 33.

    VIERULA M., KEISKI A., SAARANEN M., SAARIKOSKI S., SUOMINEN J.: High and unchanged sperm counts of Finnish men. Int. J. Androl., 1996, 19: 11–17.

    PubMed  Article  CAS  Google Scholar 

  34. 34.

    WHORTON D., KRAUSS R.M., MARSHALL S., MILBY T.H.: Infertility in male pesticide workers. Lancet 1977, 2: 1259–1260.

    PubMed  Article  CAS  Google Scholar 

Download references

Author information

Affiliations

Authors

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Auger, J., Jouannet, P. Baisse de la production et de la qualite spermatique chez l’homme: Facteurs de variation et problemes méthodologiques. Androl. 8, 9–24 (1998). https://doi.org/10.1007/BF03034758

Download citation

Mots Clés

  • fertilité masculine
  • concentration
  • qualité du sperme
  • variations

Key-Words

  • male fertility
  • sperm concentration
  • semen quality
  • secular variation
  • geographical variation
  • methodological bias