Quality of semen: a 6-year single experience study on 5680 patients

The aim of our study was to evaluate the quality of semen of a large sample from general healthy population living in Italy, in order to identify possible variables that could influence several parameters of spermiogram.

We conducted a cross-sectional study from February 2010 to March 2015, collecting semen samples from the general population. Semen analysis was performed according to the WHO guidelines. The collected data were inserted in a database and processed using the software Stata 12. The Mann-Whitney Test was used to assess the relationship of dichotomus variables with the parameters of the spermiogram; Kruskal-Wallis Test for variables with more than two categories. We used also Robust regression and Spearman correlation to analyze the relationship between age and the parameters.

We collected 5680 samples of semen. The mean age of our patients was 41.4 years old. Mann-Whitney Test showed that the citizenship (codified as "Italian/Foreign") influences some parameters: pH, vitality, number of spermatozoa, sperm concentration, with worse results for the Italian group. Kruskal-Wallis Test showed that the single nationality influences pH, volume, sperm motility A-B-C-D, vitality, morphology, number of spermatozoa, sperm concentration. Robust regression showed a relationship between age and several parameters: volume (P=0.04, R2=0.0007 β: -0.06); sperm motility A (P<0.01; R2=0.0051; β=0.02); sperm motility B (P<0.01; R2=0.02; β=-0.35); sperm motility C (P<0.01; R2=0.01; β=0.12); sperm motility D (P<0.01; R2=0.006; β=0.2); vitality (P<0.01; R2=0.01; β=-0.32); sperm concentration (P=0.01; R2=0.001; β=0.19).

Our patients had spermiogram's results quite better than the standard guidelines. Our study showed that the country of origin could be a factor influencing several parameters of the spermiogram in healthy population and through robust regression confirmed a strict correlation between age and these parameters.