Trends in sperm quality by computer-assisted sperm analysis of 49,189 men during 2015–2021 in a fertility center from China

Background Sperm quality, including semen volume, sperm count, concentration, and total progressive motility (collectively, “semen parameters”), has declined in the recent decades. Computer-assisted analysis (CASA) provides kinematic parameters, temporal trends of which remain unclear. Our objective is to examine trend both parameters Shanghai, China, years. Methods This retrospective study analyzed 49,819 men attending our reproductive center by using CASA during 2015–2021. The sample was divided into two groups: samples that surpassed WHO guideline (2010) low reference limits (“above limit” group, ARL; n = 24,575) did not (“below BRL; 24,614). One-way variance, Kruskal–Wallis test, independent t -test, covariance were used assess differences among groups. Year, age, abstinence time included multiple linear regression model ARL group adjust confounders depict quality. Results Among all BRL groups, age subjects increased Semen volume count showed tendency with years sample, subgroup or time, whereas velocities on contrary. adjusting for confirmed these trends. (β1= −0.162; CI: −0.172, −0.152), −9.97; −10.813, −9.128), concentration (β1 −0.535; −0.772, −0.299), −1.751; −1.830, −1.672), −1.12; −0.201, −0.145) decreased year, curvilinear line velocity (VCL) 3.058; 2.912, 3.203), straight (VSL) 2.075; 1.990, 2.161), average path (VAP) 2.305; 2.224, 2.386) over (all p < 0.001). In addition, VCL, VSL, VAP significantly time. Conclusion declined, We propose that, although motion increased, suggesting a possible compensatory mechanism male fertility.