DETERIORATION OF SPERM QUALITY IN YOUNG HEALTHY BELGIAN MEN

We have retrospectively analysed the sperm characteristics of 416 cons ecutive healthy young men who presented themselves in the past 19 year s as candidate sperm donors. Ejaculate volume increased slightly (P = 0.067), and average sperm concentration decreased (P = 0.035) by 12.4x 10(6)/ml over the observation period, so that sperm count per ejaculat e remained unchanged (P = 0.91), In contrast, sperm morphology (r = -0 .23, P < 0.0001), rapid progressive motility (r = -0.42, P < 0.0001) a nd total motility (r = -0.33, P < 0.0001) presented an important and t ime-related decrease. When a quadratic model was used rather than a li near one to analyse the data on rapid progressive motility, there appe ared to have been no further decline since 1990, The average proportio n of spermatozoa with normal morphology decreased from 39.2% in the pe riod 1977-1980 to 26.6% in 1990-1995 (P < 0.0001), and the mean percen tage of spermatozoa with rapid progressive motility decreased from 52. 7 to 31.7% (P < 0.0001), The percentage of candidate donors with sperm characteristics below the 5th percentile cut-off value of a normal fe rtile population increased from 13 to 54% during the observation perio d (P < 0.0001), Since the technique of semen analysis has remained ess entially unchanged in-so-far as has been practically possible, as has the method of recruitment of candidate sperm donors, the observed dete rioration of sperm characteristics is considered to reflect degenerati on of sperm production among men aged between 20 and 40 years.