Determinants associated with the variability of the sperm deoxyribonucleic acid fragmentation index in healthy men: A follow-up study

Abstract

The aim of this work was to study the variability of the sperm deoxyribonucleic acid (DNA) fragmentation index in a cohort of healthy men and to analyze the determinants and associated factors related to that variability, including sexual habits, lifestyle and environmental exposures. This is a prospective study which was carried out for 1 year evaluating multiple semen samples (obtained approximately every 4-6 weeks) from 19 healthy male volunteers. The subjects completed epidemiological questionnaires on lifestyle and environmental exposures in each of the interviews. Individuals were divided into two groups depending on their responses to several lifestyle and environmental exposure questions (“yes” vs. “no”). The coefficient of variation (CV) and the intra-subject coefficient of variation (CVi) of the sperm DNA fragmentation index were calculated and their statistical differences examined with regard to their responses to the studied factors. The CVs of the the sperm DNA fragmentation index were significantly different for all the studied variables, with the exception of the exposure to environmental toxicants (similar CV) and light physical exercise (similar CVi). That index was also positively correlated to the number of hours spent doing sedentary activities (p-value = 0.05). As with the analysis of conventional semen parameters, a single analysis of the sperm DNA fragmentation might be scarcely realiable to determine that parameter in men. Our study shows that certain male factors or characteristics may be related to a higher or lower variability of the sperm DNA fragmentation index.