Seasonal changes in human sperm chromatin condensation

Purpose: The aim of this study was to investigate possible seasonal changes in human sperm parameters, especially chromatin condensation.Method: In a first run, 3155 patients attending the andrological outpatient clinic at the Centre of Dermatology and Andrology at Justus Liebig University, Giessen, Germany, from January 1992 to October 1995 were examined for sperm count, motility, vitality, and chromatin condensation.Results: The respective results were correlated according to season. Significant seasonal changes were observed in chromatin condensation and sperm count, with mean maximum values (for chromatin condensation and sperm count) of 86.24% aniline blue-negative spermatozoa in January and 68.75 × 10⁶mL^–1 in April. To confirm the observation of seasonal changes in sperm chromatin condensation in Germany on the Southern Hemisphere, 179 patients attending the Reproductive Biology Unit at Tygerberg Hospital, Tygerberg, South Africa, were examined by means of the aniline blue stain from April 1999 to April 2000. For chromatin condensation, a significant seasonal change shifted by 4–5 months was observed on the Southern Hemisphere. However, no seasonal variations could be found for the sperm count.Conclusions: Our results clearly demonstrate seasonal changes in sperm count and chromatin condensation. In contrast, no circannual relation was observed for motility and vitality.