Chang, S., Nazem, T. G., Gounko, D., Lee, J., Bar-Chama, N., Shamonki, J. M., Antonelli, C., & Copperman, A. B., “Eleven year longitudinal study of U.S. sperm donors demonstrates declining sperm count and motility,” Fertility and Sterility, 2018, 110(4), e54-e55. DOI: 10.1016/j.fertnstert.2018.07.170.
ABSTRACT:
OBJECTIVE: Physicians and public health experts have been investigating whether there is evidence of deterioration in semen quality.1-3 Investigators who believe in a decline point to the concomitant increase in the incidence of genitourinary abnormalities.3-5 Others have focused on increased exposure to environmental endocrine disruptors and changes in diet and BMI. One obstacle to understanding male fertility is possible geographic variations in semen quality, which may be due to differences in climate, pollution, occupational exposure, lifestyle, and social habits. This study sought to evaluate semen quality in geographically diverse US sperm donors.
DESIGN: Retrospective.
MATERIALS AND METHODS: Semen analyses (SA) from 2007-2017 were examined. The sperm donors (ages 19-38) originated from Los Angeles, Palo Alto, Houston, Boston, Indianapolis and New York City. Total sperm count, average concentration and total motile count were analyzed as a whole and by region. Data was analyzed using a general estimate equation model with an exchangeable working correlation structure.
RESULTS: A total of 124,107 SA specimens were analyzed. Controlling for BMI, there was a decline in total sperm count (b¼-2.9, p<0.01), concentration (b¼-1.76, p<0.01) and total motile sperm count (b¼-2.45, p<0.01) over the 11-year study. There were decreases in SA parameters in all regions except New York City, which showed no change in total sperm count, concentration or total motile sperm count. Boston showed a decline in concentration and total motile sperm count but no difference in total sperm count.
CONCLUSIONS: Changes in our modern environment—chemical exposures or increasingly sedentary lifestyles—may negatively affect spermatogenesis. We demonstrated a time-related decline in semen quality. Given that donors have higher than average sperm counts, these trends would likely be magnified in the general population. If confirmed, these findings would serve as a public health warning, particularly with the simultaneous increase in other male disorders, including testicular cancer.5 The magnitude of semen quality decline varied by region, with only samples from New York City consistent throughout the study. To further investigate geographical differences, future prospective studies should investigate potential causes for this decline. Identifying modifiable risk factors is the first step in determining how to reverse these trend.