The phenomenon of seasonal variation has been recorded for semen, and therefore a significant fluctuation in its quality can be observed over time.

Is my sperm always the same?? – Seasonal variation of sperm

An extremely interesting phenomenon that has been recorded is the seasonal variation of sperm, that is, the fluctuation of its quality over time. Numerous studies document variations in parameters such as concentration, motility, sperm morphology and DNA quality. The intensity of the fluctuation varies and there are cases where a large difference is observed between different downloads.

The example of the diagram of the W.H.O. manual is typical. (1999) where the fluctuation of the sperm concentration of a fertile man over a period of two and a half years (120 weeks) is illustrated. The range of variation is remarkable as concentration levels quite high (170,000,000/ml) to below the reference limit (below 15,000,000/ml) have been recorded.

The results of research concerning Mediterranean countries, confirm the seasonality in sperm quality and furthermore note an upward trend after winter (March-April) and a corresponding decrease after summer (September). This fact is also evident in the frequency of births observed during the year, as there is a decrease in the spring due to the reduced possibility of conception in the summer.

The factors that probably explain this phenomenon are the changes in temperature and length of day that accompany the change of seasons. The high temperature observed during the summer months has a negative effect on the spermatogenesis process with the result that lower levels of sperm quality are observed during this period as well as in the first months of autumn. In addition, according to recent research, the duration of sunshine also seems to have a significant effect, through the regulation of melatonin. Melatonin is a hormone produced in the brain in response to darkness and regulates the daily cycle and sleep. Increased levels of melatonin improve sperm concentration, propulsive motility, as well as their morphology. During the winter, the reduced length of the day favors the secretion of melatonin and, by extension, the improvement of sperm quality.

The phenomenon of sperm variation affects the interpretation of the result of the sperm diagram, especially in the case of low quality sperm. This practically means that the safest strategy is to repeat a sperm test at least twice a year, with a time interval of at least 3 months between the two tests, in order to have a thorough picture, without however predetermining the result from the time of day or the time of year when the exam is being held.