Objective: To study the impact of sperm DNA fragmentation (DF) on the outcome of frozen-thawed blastocyst transfer in in vitro fertilization and embryo transfer (IVF-ET).
Methods: We retrospectively analyzed 308 cases of routine IVF-ET performed at our Center of Reproductive Medicine from January 2016 to January 2018. According to the sperm DNA fragmentation index (DFI), we divided the patients into a normal DFI (DFI ≤ 15%, n = 114), a moderate DFI (15% < DFI ≤ 30%, n = 103), and a high DFI group (DFI > 30 %, n = 91), and compared the development of embryos and clinical outcomes among the three groups.
Results: The blastocyst formation rate was remarkably higher in the normal and moderate DFI groups than in the high DFI group (68.9% and 66.2% vs 58.3%, P < 0.05) but the percentage of available blastocysts exhibited no statistically significant difference between the former two and the latter group (88.1% and 84.0% vs 81.2%, P > 0.05). There were statistically significant differences among the normal, moderate and high DFI groups in the percentage of high-quality blastocysts (80.3% vs 68.8% vs 59.7%, P < 0.05). The implantation rate was dramatically lower in the high DFI group than in the normal and moderate DFI groups (30.4% vs 43.1% and 41.0%, P < 0.05), and so was the clinical pregnancy rate (33.6% vs 43.2% and 40.2%, P < 0.05), but the abortion rate markedly higher in the former than in the latter two groups (16.2% vs 10.0% and 9.8%, P < 0.05).
Conclusions: High sperm DFI can not only significantly reduce the rates of blastocyst formation, available blastocysts and high-quality blastocysts, but also decrease the rates of implantation and clinical pregnancy and increase that of abortion after frozen-thawed blastocyst transfer.
Keywords: blastocyst; in vitro fertilization and embryo transfer; pregnancy rate.; sperm DNA fragmentation index.