Sperm DNA Fragmentation in Normospermic and Oligospermic Men Is Associated with Blastocyst Formation and Quality in Conventional In Vitro Fertilization

Background: Assisted reproductive therapy (ART) has been utilized as an effective therapeutic strategy for addressing infertility worldwide, and one of the key determinants of ART success is the acquisition of high-quality embryos through in vitro fertilization (IVF). We investigated here which male factors were associated with embryo formation and quality in conventional IVF (cIVF). Methods: This study was a sub-analysis of a trial conducted to examine the associations of clinical and lifestyle factors with sperm abnormalities in 42 men of infertile couples without identifiable male factor infertility. From the original cohort, 21 men whose partners underwent cIVF were included. Semen samples were evaluated for standard sperm parameters and DNA fragmentation index (DFI). Blood biochemical parameters and lifestyle habits were also evaluated. Blastocysts were assessed 5 days after cIVF, and implantation success was determined 10 days after embryo transfer. Results: Normospermia and oligospermia were observed in 67% and 33% of participants, respectively, with mild sperm DFI in 76%. Blastocysts were formed in 32% of the oocytes following cIVF. Among them, good blastocyst development and quality were observed in 71% and 39%, respectively. Eighteen women underwent blastocyst transfer, resulting in an implantation success rate of 50%. Multiple regression analysis identified sperm DFI as the only variable inversely associated with blastocyst outcomes. In contrast, only female age was associated with implantation success. Conclusions: The present findings suggest that sperm DNA fragmentation may negatively affect high-quality embryo formation in cIVF, even among normospermic and oligospermic men with non-severe sperm DFI.