Analysis of seasonal variability of sperm donors’ semen parameters

Introduction. The concept of seasonal variability of sperm parameters is controversial. However, it should be considered during medical evaluation and solicitation of sperm donors.

Aim. To evaluate seasonal variability of sperm parameters from anonymous sperm donors in a reproductive medicine center.

Materials and methods. A retrospective study of 1252 semen samples from 39 sperm donors (mean age 27.1 ± 3.9 years) in a reproductive medicine center in Saint Petersburg during the period from October 1, 2015 to October 1, 2017 was performed according to WHO 2010 recommendations. Semen volume, sperm concentration, total sperm number, progressive motility, and number of progressively motile sperm were analyzed.

Results. Individual variability in semen parameters was high. The mean ejaculate volume in the summer months was higher than in the autumn, winter, and spring (t = 3.65, p < 0.001; t = 4.18, p < 0.0001; t = 1.92, p = 0.056 respectively). The lowest volume (2.83 ± 1.32 ml) was registered in January. The mean sperm concentration in summer was lower than in autumn, winter, and spring (t = 3.65, p < 0.001; t = 4.18, p < 0.0001; t = 1.92, p = 0.056 respectively). It was higher in winter than in spring and autumn (t = 2.54, p = 0.012; t = 1.72, p = 0.082 respectively). The highest mean sperm concentration was registered in January and the lowest in July (157.2 ± 46.6 and 131.9 ± 44.0 million sperm per ml, respectively). No significant seasonal differences were found in total sperm number, progressive motility, or number of progressively motile sperm (p > 0.1).

Conclusions. The study suggests there is both individual and seasonal variability in sperm donors’ semen parameters. As several semen samples are needed to rate semen quality, we recommend that semen analysis for a potential sperm donor be performed in the summer months.