Background: Sperm DNA fragmentation (SDF) has emerged as an important biomarker of male fertility, with growing evidence linking elevated SDF levels to impaired embryo development. However, the precise threshold of SDF that significantly influences blastocyst formation and quality remains controversial. Understanding this relationship is crucial for optimizing ART outcomes and counselling couples with male factor infertility.

Aim: To evaluate the impact of different sperm DNA fragmentation thresholds on fertilization, cleavage, and blastocyst development, and to determine the cutoff value most strongly associated with adverse embryological outcomes.

Methods: This retrospective study analyzed ICSI cycles performed at a tertiary fertility center. Patients were categorized into three groups based on SDF levels measured by the sperm chromatin structure assay (SCSA):

• Group A: <15%
• Group B: 15–30%
• Group C: >30%

Primary outcomes assessed included fertilization rate (FR), day-3 cleavage rate, blastocyst formation rate (BFR), and usable blastocyst rate (UBR). Statistical comparisons were made using ANOVA and multivariate regression to adjust for confounders such as age, AMH, and oocyte yield.

Results: Blastocyst formation rates decreased significantly with rising SDF levels:

• Group A: 62%
• Group B: 48%
• Group C: 28% (p<0.01)

Similarly, usable blastocyst rate was markedly reduced in Group C compared with Groups A and B. Fertilization and cleavage rates showed modest decline but were less strongly correlated with SDF levels. An SDF threshold of ≥30% was identified as the point at which blastocyst development was most adversely affected.

Conclusion: Higher sperm DNA fragmentation, particularly levels exceeding 30%, is strongly associated with reduced blastocyst formation and quality in ICSI cycles. SDF testing should be considered in couples with recurrent blastocyst arrest, unexplained infertility, or male factor issues. Targeted interventions—antioxidant therapy, lifestyle modification, and advanced sperm selection methods (MACS, microfluidics)—may help improve outcomes in high-SDF individuals. Further prospective studies are warranted.

Ratna Agrawal holds an M.Sc. in Clinical Embryology from the University of Leeds, United Kingdom, and a PhD. She is a Senior Embryologist and currently serves as the Director of Ashoka Super Speciality Hospital & Research Pvt. Ltd. With extensive expertise in clinical embryology and assisted reproductive technologies, she is actively involved in advancing reproductive medicine through clinical practice, leadership, and research.