Association of sperm DNA fragmentation index with semen quality and ART outcomes: real-world evidence from a retrospective cohort.

BACKGROUND: Sperm DNA fragmentation index (DFI) has emerged as a potential marker of male fertility, but its clinical value in assisted reproductive technology (ART) remains debated. This study aimed to investigate the association between sperm DFI and conventional semen parameters, embryological outcomes, and pregnancy outcomes in ART, using a large real-world dataset. RESULTS: A total of 1,784 ART cycles performed at a single center between January 2020 and January 2022 were analyzed. Patients were categorized into normal (< 30%) and high (≥ 30%) DFI groups. Compared with the normal DFI group, men with high DFI had significantly lower sperm concentration (B = − 31.15, 95% CI: − 44.75 to − 17.55), progressive motility (B = − 12.21, 95% CI: − 14.87 to − 9.56), and total motility (B = − 18.00, 95% CI: − 21.38 to − 14.62; all P < 0.001). After adjusting for female and male factors, high DFI was associated with a significantly lower 2PN fertilization rate (β = − 0.257, 95% CI: − 0.491 to − 0.024, P = 0.031), while no significant differences were observed in top-quality embryo rate, transferable embryo rate, or pregnancy outcomes. Sensitivity analyses using alternative statistical methods (ZOIB and PSM) and varying DFI thresholds (25% and 35%) yielded results completely consistent with the main analyses. CONCLUSIONS: High sperm DFI is independently associated with poorer semen quality and a reduced 2PN fertilization rate but was not significantly associated with embryo quality or pregnancy outcomes in this study. These findings support the clinical relevance of DFI in evaluating male fertility potential while suggesting its limited predictive value for ART success when female and cycle-related factors are considered.