Data from men in greater Seattle area reveals no downward trend in semen quality: further evidence that deterioration of semen quality is not geographically uniform

To determine whether there has been a decline in semen quality in a group of healthy men during the past 21 years. Retrospective analysis of the relationship between time and changes in semen parameters over 21 years using regression analysis. A tertiary university center. Five hundred ten healthy, normal men who donated multiple semen samples as participants in clinical studies between 1972 and 1993. Sperm concentration, semen volume, total numbers of sperm per ejaculate, and percent spermatozoa with normal morphology. There was no decrease in sperm concentration, semen volume, total number of sperm per ejaculate, and percent normal sperm morphology in 510 healthy men studied between 1972 and 1993. We conclude that in this population of healthy young men there has not been any decline in semen quality in the past 21 years.