The influence of individual and environmental factors on sperm DNA fragmentation index and its association with IVF outcomes

Objective: To investigate the influence of age, body mass index (BMI), varicocele, diabetes, tobacco use, and environmental occupational risks on sperm DNA fragmentation index (DFT) and its association with semen parameters and in vitro fertility (IVF) outcomes. Methods: This cross-sectional study was conducted on 116 infertile men. Conventional semen parameters were analyzed according to the World Health Organization criteria. Sperm DNA fragmentation was evaluated using sperm chromatin dispersion method. After visiting the infertility center, the men's height and weight were measured, and blood tests were performed to check for diabetes, and medical records were reviewed for varicocele, tobacco use, and type of occupation. The sperm was then examined for DFI. Then, the association between sperm DFI and IVF failure rate was investigated. Results: The study showed a significant association between DFI≥20% with BMI ( OR 1.134, 95% CI 1.04-1.24, P =0.006), varicocele ( OR 4.330, 95% CI 1.25-14.96, P =0.021), tobacco use ( OR 3.066, 95% CI 1.06-8.90, P =0.039) and environmental and occupational risks ( OR 2.694, 95% CI 1.08-6.75, P =0.034) as well as sperm motility ( P <0.05). Although the amount of DNA damage increased in those aged ≥40 years, there was no significant association between the amount of DFT ≥20% and age, diabetes, sperm volume and concentration, morphology and progressive rate ( P >0.05). The IVF failure rate was higher in people with a DFI ≥20%. Conclusions: Factors such as BMI, varicocele, improper working conditions and environment cause damage to sperm DNA, and DFI ≥20% damage can have adverse effects on IVF outcomes.