Chronobiological fluctuations in semen parameters with a constant abstinence period

This study examined the seasonal variation in three semen parameters (total sperm count, % grade a progressive motility and sperm morphology according to strict criteria) with an identical abstinence period of 24 h. A total of 340 spermiograms of 107 different men enrolled in an intrauterine insemination (IUI) program were examined. To reduce variation due to interindividual disparities in semen quality, differences of each test result from the mean value obtained for that individual were analyzed. Mean values resulted from at least 3 observations during different IUI cycles. Using ANOVA and spectral analysis, no differences in semen parameter results in function of the month of the year were observed. The lack of any significant periodicity may be explained by the large biological variation for individual semen parameters and/or the lack of significant differences regarding light exposure and temperature between summer and winter months in moderate climates.