Changes in seminal parameters among Brazilian men between 1995 and 2018

Aiming to investigate trends in seminal parameter values among Brazilian men between 1995 and 2018, we performed a retrospective analysis of spermograms of couples admitted for infertility testing at UNICAMP/Brazil. For the present study, only the first sample produced by each man was analyzed (9,267 samples). Total motile sperm count (TMSC), percentage of spermatozoa with normal morphology (NM), and sperm concentration after seminal processing (SCA) were considered dependent variables. Statistical analysis was carried out through linear regression for the median values both in the general population and in the population categorized by age group (<30, 30–39, and ≥40 years). During the study period, the mean age of men was 32.46 (± 6.48) years, with a median of 32 (18–67) years. We found a significant decrease in the median values of TMSC (reduction of 2.84 million/year), NM (reduction of 0.52% each year) and SCA (reduction of 0.24 million/mL each year). In conclusion, we observed that Brazilian men undergoing infertility investigation had a decline in seminal parameters in the past 23 years. Surveillance should be maintained in the coming years, and further studies are needed to elucidate possible causes for seminal deterioration and to devise strategies to reverse this trend.