East-West gradient in semen quality in the Nordic-Baltic area: a study of men from the general population in Denmark, Norway, Estonia and Finland.
BACKGROUND
Denmark and Norway have a three-fold higher incidence of testicular cancer than Estonia and Finland. Groups of young men from Denmark, Norway, Finland and Estonia were investigated to elucidate whether semen parameters and other related parameters follow a gradient between these countries, as does the gradient in incidence of testicular cancer.


METHODS
In total, 968 young men from the general population in these four countries were investigated according to the same protocol. Possible confounders were evaluated, and included in the statistical analysis when appropriate. Inter-laboratory differences in assessment of sperm concentrations were controlled by an external quality control programme and morphology assessment was centralized to one person.


RESULTS
The Finnish and Estonian men had an adjusted median sperm concentration of 54 and 57 x 10(6)/ml, respectively and the Norwegian and Danish men 41 x 10(6)/ml. The corresponding total sperm counts were 185, 174, 133 and 144 x 10(6). The frequency of normal sperm in men from Finland was 8.9%, Estonia 9.2%, Norway 6.9% and Denmark 6.4%. Within all four groups of men, a relationship between increasing levels of inhibin-B and increasing sperm counts was observed. However, inhibin-B levels were not predictive of sperm count differences between countries.


CONCLUSIONS
It is believed that the men examined were representative of the normal population of young men in all four countries as they were recruited from groups attending a compulsory medical examination, and not selected for known fertility or semen quality. Moreover, the majority of participants had no prior knowledge of their fertility potential. It appears that an east-west gradient exists in the Nordic-Baltic area with regard to semen parameters, this being in parallel with the incidences of testicular cancer. Further investigations are required to determine whether these findings are due to genetic differences, to different environments, or perhaps to a combination of both factors.
Jørgensen
Niels
N
Department of Growth and Reproduction, Rigshospitalet, The Juliane Marie Centre, Copenhagen, Denmark. njcph@rh.dk
Carlsen
Elisabeth
E
Nermoen
Ingrid
I
Punab
Margus
M
Suominen
Jyrki
J
Andersen
Anne-Grethe
AG
Andersson
Anna-Maria
AM
Haugen
Trine B
TB
Horte
Antero
A
Jensen
Tina Kold
TK
Magnus
Øystein
Ø
Petersen
Jørgen Holm
JH
Vierula
Matti
M
Toppari
Jorma
J
Skakkebaek
Niels E
NE
D000328:Adult; D003710:Demography; D003718:Denmark; D004957:Estonia; D005387:Finland; D006801:Humans; D007265:Inhibins / Q000097:blood; D008297:Male; D009664:Norway; D012661:Semen / Q000502:physiology*; D013076:Sperm Count
C422364:inhibin B; D007265:Inhibins