Abstract

PIP: Comparison of data from 1951 and from 1966-77 indicates that there has been no substantial change in the numerical aspect of semen quality over this period. Other researchers have suggested that a depression of spermatogenesis has occurred in US males. The 1951 baseline data are taken from MacLeod and Gold's study of 1000 "infertile marriage" patients. Modern trends are extrapolated from the authors' survey of the ejaculate volume and sperm counts in 14,476 men evaluated in 1966-77 because of infertile marriages. 9000 of these men were receiving their 1st semen examination, whereas 5476 had been examined elsewhere prior to referral. Semen specimens were obtained by masturbation after 3 days of continence in both studies. Over time, no consistent trend in sperm count was detected. The median count among the 1000 men examined in 1951 was 74 million/ml, whereas the median among the 9000 men examined sequentially in 1966-77 was 76.5 million/ml. In terms of the overall count frequency distribution, 16% of those in the 1951 study fell in the or= 20 million/ml class compared with 15.1% of those in the 1966-77 study group. The proportions of those in the 100 million/ml group were 38% and 36.5%, respectively. None of these differences are significant. The average ejaculate volume of the 14,476 recent patients remained stable at 3.2 ml throughout the study period. Most notable was the orderly nature of the sperm count frequency distributions around the medians over the 1966-77 decade. Critical analysis of other studies from the 1951-77 period points to the need for clear definition of the types of populations studied since population nuances can produce some divergent results. For example, subjects from infertile marriages appearing for their 1st semen examination have the best semen qualtiy of any infertility population. Although no change was noted in semen quality standards, the authors concur with earlier suggestions that the minimal standards recommended by the American Fertility Society be modified. It is particularly urged that the present minimum sperm count of 40 million/ml be reduced and accompanied by a rider that any count level is meaningless unless the sperm motility parameter is included. Future articles will focus on changes in the qualitative aspects of ejaculate, sperm motility, and sperm morphology. The authors expect to demonstrate that significant changes have occurred in these parameters since 1951.