Regional differences in semen quality in Europe

Changes in male reproductive health and effects of endocrine disruptors in Scandinavian countries

Male reproductive health has deteriorated in many ways during the last decades. The incidence of testicular cancer has rapidly increased in Europe and European-derived populations. Sperm concentrations have declined and sperm motility and morphology have worsened in many areas. Both adverse trends have been shown to be associated with year of birth. Older birth cohorts have better reproductive health than the younger generations. Incidences of cryptorchidism and hypospadias have also increased according to several studies. The reasons for secular trends are unknown, but the rapid pace of the change points to environmental causes. Endocrine disrupting chemicals have been hypothesized to influence male reproductive health.

Sperm morphological defects related to environment, lifestyle and medical history of 1001 male partners of pregnant women from four European cities

BACKGROUND

Recently, differences in semen quality have been found among the partners of pregnant women from four European cities: Turku, Copenhagen, Edinburgh and Paris.

METHODS

During this study, slides from the four centres were subjected to a centralized assessment of sperm morphology. The percentages of sperm defects were recorded using a multiple-entry classification enabling the calculation of the multiple anomalies index (MAI), which is the mean number of anomalies per abnormal sperm. The relationships between various sperm abnormalities and self-reported data on medical history, lifestyle and occupational factors were examined.

RESULTS

Significant differences in the MAI and most of the sperm defects were found between the four cities, and more abnormalities were found in spring than in winter. An increase in some sperm abnormalities was related to medical treatment of the mother during pregnancy, higher birthweight and previous treatment for cryptorchidism. Significant variations of several sperm defects were related to stress, weekly working time, occupational posture and metal welding, suggesting directions for further exposure studies.

CONCLUSION

The present study indicated that the detailed assessment of sperm abnormalities is a useful biomarker of the effect of various external factors which may qualitatively affect human spermatogenesis.

Regional differences in waiting time to pregnancy among fertile couples from four European cities

BACKGROUND

A previous European study found a longer time to pregnancy (TTP) among fertile women from Paris compared with women from other Western European countries. A co-ordinated, cross-sectional study of pregnant couples from Denmark (Copenhagen), France (Paris), Scotland (Edinburgh) and Finland (Turku) was therefore undertaken to assess differences in waiting TTP among couples from these cities.

METHODS

Pregnant women were invited to participate when they showed up for their first antenatal visit in one of the four centres. Inclusion criteria included that their partner was 20-45 years of age and born in the country in which he was currently living and that the pregnancy was achieved without fertility treatment. Both partners filled in a questionnaire and the man underwent a physical examination and delivered a semen sample (Turku: n = 237, Copenhagen: n = 302, Edinburgh: n = 212, Paris: n = 191).

RESULTS

French couples had a decreased probability of conception compared with couples from the other three countries, although only after adjustment for confounders. No significant differences between couples from the three other countries were found.

CONCLUSION

The observed geographical differences in TTP remain unexplained and were not due to differences in semen quality, but may be caused by varying exposures to environmental factors or psychological distress. In addition, selection bias due to the low participation rates cannot be ruled out. Future studies examining the causes for geographical differences in TTP are needed.

Hormones and testis development and the possible adverse effects of environmental chemicals

Development of a fetus into a phenotypic male depends, first, on testis formation and second, on hormone production by the fetal testis. Disorders of testicular hormone production or action can lead in severe cases to phenotypic abnormalities or can predispose towards impaired reproductive health. Evidence for deteriorating human male reproductive health, especially an increase in testicular cancer, points to disturbed (hormonal) development of the fetal testis. By comparison of testicular dysgenesis in humans and exposure to certain phthalates in fetal rats, the similarities in outcomes and testicular cell-cell disruption are highlighted as are the pathways via which oestrogenic and (especially) anti-androgenic environmental chemicals might act to induce such changes. The susceptibility of sperm production in adulthood to 'hormonal' disruption in fetal and neonatal life is also discussed. Though it is concluded that no direct evidence links human exposure to environmental chemicals and male reproductive disorders that stem from disturbed testis development, this is based mainly on lack of information. Using the example of phthalates, for which new data have emerged, it is argued that until the appropriate in vivo studies are undertaken, the safety of hormonally active environmental chemicals, especially in mixtures, will continue to give cause for concern as far as testicular development is concerned.