Body mass index and sperm morphology as independent predictors of increased sperm DNA fragmentation after cryopreservation in men with severe oligoasthenoteratozoospermia.

BACKGROUND: Semen cryopreservation is vital for fertility preservation in men with oligoasthenoteratozoospermia (OAT). While cryopreservation increases sperm DNA fragmentation (SDF), patient-specific risk factors in severe OAT remain poorly defined. We aimed to quantify the change in DNA fragmentation index (DFI) and identify clinical predictors of susceptibility. METHODS: This retrospective cohort study enrolled 340 men with severe OAT (sperm count < 5 million/mL, total motility < 42%, progressive motility < 30%, morphology < 4%). DFI was assessed in fresh and post-thaw samples using the TUNEL assay. Correlations and multivariate regression analyses evaluated relationships between DFI change and age, body mass index (BMI), sperm parameters, and smoking status. RESULTS: The mean DFI increased significantly from 22.0% (IQR 15.0-29.0%) in fresh semen to 36.0% (IQR 23.0-54.0%) postcryopreservation (p < 0.001). The median absolute increase (ΔDFI) was 9.5% (IQR 6.0-25.0%). Univariate analysis identified significant correlations between the ΔDFI and higher BMI (ρ = 0.544, p < 0.001), lower sperm count (ρ = -0.638, p < 0.001), and poorer sperm morphology (ρ = -0.669, p < 0.001). In the final multivariate linear regression model, higher BMI and poorer sperm morphology remained the only significant independent predictors of a greater increase in DFI after cryopreservation (both p < 0.001). This model explained 93.7% of the variance in the ΔDFI (Adjusted R² = 0.937, p < 0.001). Age and sperm count were not independent predictors in the final model. Smoking status and varicocele grade were not significantly associated with the ΔDFI. CONCLUSIONS: Cryopreservation significantly exacerbates sperm DNA damage in severe OAT, but this effect is not uniform. Higher BMI and poorer sperm morphology are independent risk factors for greater damage, identifying a vulnerable patient subgroup. These men may benefit from personalized counseling and optimized cryopreservation protocols to mitigate DNA damage and improve future assisted reproductive technology outcomes.