Sperm Quality and Environment: A Retrospective, Cohort Study among 21,715 Semen Samples in a Southern Province of China

To explore the differences of male semen parameters in different seasons of the year, so as to explore the potential climatic factors affecting spermatogenesis and male reproductive ability, we retrospectively analyzed 21,715 semen analysis data from January 2018 to February 2021, grouped by year and season, and finally the relationships among semen parameters and semen and meteorological parameters were compared. Environmental exposures prior to 3 months were analyzed and correlation analysis was performed.The semen concentration decreased year by year (p < 0.01). However, the Progressive motility (PR) and total PR number had been increased (p < 0.01). There were statistical differences in sperm parameters which include semen volume, sperm concentration, total sperm number, progressive motility (PR), total PR number and total motility in different seasons, winter and spring were better than summer and autumn (p < 0.01). Total sperm number and sperm concentration were positively correlated with PR (R = 0.420, R = 0.440, p < 0.01). There was no correlation between daylight duration and semen parameters. Sperm parameters were positively or negatively correlated with environmental temperature, air pressure or humidity which had an overall effect on semen quality. It is suggested that seasonal factors should be considered when evaluating male reproductive ability. Besides referring to conventional semen parameters, other factors such as season and climate should also be considered.