Seasonal variation and age-related changes in human semen parameters

Although semen quality has been discussed extensively with regard to age and season in the andrology literature, the results vary and firm conclusions are still outstanding. To investigate seasonal and age-related variations in human semen parameters, we analyzed data that were collected from an andrology clinic population. We performed a retrospective review of 551 semen analysis records collected from 1989 to 2000 from the Vincent Memorial Andrology Laboratory at Massachusetts General Hospital. Semen volume, sperm concentration, total sperm count, motility, total motile sperm, and morphology significantly decreased as age increased. In addition, as age increased, the percentage of sperm with tail defects increased. Sperm concentration was significantly higher in winter (mean 157.9 million/mL) than in fall (mean 119.1 million/mL) (P <.05). The mean percentage of sperm with normal morphology was significantly higher in winter (9.2%) than in summer and spring (7.0% and 7.5%, respectively; P <.05). The mean percentage of sperm with head defects was significantly higher in fall and summer (74.0% and 72.3%, respectively) than in winter (68.6%; P <.05). Seasonal variations were found in sperm concentration and morphology, with higher sperm concentrations in winter than in fall, and a greater percentage of sperm with normal morphology in winter than in spring and summer. Sperm concentration was lowest in the fall, whereas the percentage of sperm with normal morphology was lowest in summer. Semen volume, sperm concentration, total sperm count, motility, total motile sperm, and morphology decreased as age increased.