Semen quality evaluation in a cohort of 28213 adult males from Sichuan area of south-west China

The trends in semen quality are conflicting. Although many previous surveys on semen quality indicated a decline, the trends in semen quality in Sichuan area of south-west China are not clear. We analysed the semen parameters in a cohort of 28,213 adult males close to general population in Sichuan between July 2007 and June 2012, and investigated the changes on semen quality. The semen parameters including pH, volume, concentration, motility, morphology were measured according to the World Health Organization (WHO) criteria. Kruskal-Wallis analysis of variance was used to examine the statistical differences of semen quality between groups. We found that the medians (5th and 95th percentiles) were 2.4 ml (1.0-5.0) for semen volume, 62.0 × 10(6) ml(-1) (15.0-142.0) for semen concentration, 39% (18-60%) for sperm progressive motility and 10.5% (1.0-34.5%) for normal morphology. In these 5 years, sperm concentration and the percentage of sperm normal morphology were decreased from 66.0 × 10(6 ) ml(-1) to 49.0 × 10(6) ml(-1) and from 13.5% to 4.5%, respectively; among different reproductive history groups, sperm concentration and the percentage of sperm normal morphology were also decreased in these 5 years. And the incidence of azoospermia was increasing. These may imply that there is a decline in semen quality of adult males in Sichuan area.