Abstract
            Background. Sperm motility is a fundamental factor for sperm penetration into the  oocyte and fertilization. According to the World Health Organization (WHO)  2021, less than 42% of motility is called asthenozoospermia, which is one of  the most common causes of male infertility. This retrospective cohort study  aims to investigate sperm DNA damage with TUNEL and SCSA methods and its  relationship with sperm parameters, age, and body mass index (BMI) in severe  asthenospermia (<2% sperm motility) and normozoospermia.  
    Methods. The study parameters  between 111 subjects with severe asthenozoospermia and 113 subjects with  normozoospermia were investigated. The 2010 World Health Organization  guidelines were used to evaluate sperm parameters, and TUNEL and SCSA methods  were used to assess sperm DNA damage. The statistical analysis was done using  the t-test of two independent samples. Pearson's correlation coefficient was  used to investigate the relationship between sperm DNA damage and sperm  parameters, age, and BMI P<0.05 was considered significant.  
    Results. The mean seminal  volume, sperm concentration and count, and the percentage of sperm total  motility and progressive motility were significantly lower in severe  asthenospermic subjects compared to normozoospermic subjects (P<0.001).  In addition, the mean percentage of sperm DNA damage in severe  asthenozoospermic individuals was significantly higher than in normozoospermic  individuals (P<0.001). There was also a positive and significant  relationship between sperm DNA damage and the age of severely asthenozoospermic  men.  
    Conclusion. Sperm motility, sperm  DNA damage, and the father's age are essential in the successful conception,  development, and health of the embryo. Therefore, the evaluation of sperm DNA  damage is recommended in examining male fertility and selecting the appropriate  treatment approach for men with severe asthenozoospermia.
    Practical Implications.  Considering that the  sperm genome constitutes 50% of the genetic material of the next generation,  evaluating sperm DNA health to determine the appropriate treatment approach in  infertile men can be influential in the success of assisted reproductive  techniques and in maintaining the next generation’s health.