Comparison of sperm counts in two groups of men presenting for infertility investigations 20 years apart.

Abstract

Aims:  To compare sperm counts for two groups of men who had presented for infertility investigations approximately 20 years apart. Methods:  The study compared results for 309 men tested between 1977 and 1981 with those of 559 men tested between 1997 and 1998 using identical methodology. In order to approximate the normal population, only those men with counts above 5 million/mL were included in the final analysis. Bias, due to repeated testing after an initial abnormal result, was minimized by including only the patient's first test results. In addition, to allow for time-dependent changes in the requirements for semen samples, results were included only if a complete sample was produced b..