Seasonality in human semen quality of smokers and non-smokers: effect of temperature.
OBJECTIVE
To analyse the possible effect of seasonal variation on semen parameters.


METHODS
The participants consisted of 1,688 men attending the andrology laboratory between 1991 and 1997 for reduced fertility in the couple. Semen analysis was performed according to the WHO manual. The 84 individual months of the study period were each assigned to one of the three groups according to the average monthly outside temperature; Group A (temperature < 4.4 degrees C), Group B (4.4 degrees C - 13.3 degrees C) and Group C (>13.3 degrees C).


RESULTS
When comparing the different sperm parameters, the morphology was significantly better in Group C. However, when the smokers were analysed separately, this difference disappeared and significant seasonal variations were found in sperm density, total sperm count, motility and total motile sperm; they were deteriorated in the warmer season. In non-smokers, no such negative effect of increased temperature was observed.


CONCLUSIONS
Sperm quality is influenced by seasonal factors. Increased environmental temperature, (maybe also light exposure) has an additional negative effect on the spermatogenesis in smokers, leading to reduced sperm quality in men with borderline fertility.
University Department of Clinical Research, Inselspital KKL G3-825, Berne CH-3010, Switzerland.
Robert
R
Künzle
Michael D
MD
Mueller
Alexander W
AW
Huber
Heinz
H
Drescher
Nick A
NA
Bersinger
D000328:Adult; D005298:Fertility / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D012016:Reference Values; D012621:Seasons; D012661:Semen / Q000502:physiology*; D012907:Smoking / Q000503:physiopathology*; D013076:Sperm Count; D013081:Sperm Motility; D013557:Switzerland; D013696:Temperature