Replication Data for: Seasonal Trends in Sperm Quality in Denmark and Florida

Strong and consistent seasonal variation was observed in the concentrations of progressively motile (grades a and b) sperm in both Denmark and Florida. The concentration of rapidly progressive (grade a) sperm was highest in the warmer months (May-July) and lowest in the colder months (October-March) in both countries, despite climatic and demographic differences. There was no evidence of seasonal variation in ejaculate volume or total sperm concentration, indicating that the rate of spermatogenesis did not vary seasonally. The Total Motile Sperm Count (TMSC) also varied seasonally, even after controlling for average daily temperature in the contemporaneous and preceding months, suggesting that other seasonal factors, possibly related to lifestyle or environment, may affect sperm motility.