Random sperm DNA fragmentation index is not associated with clinical outcomes in day-3 frozen embryo transfer

Damage to sperm DNA was proposed to play an important role in embryonic development. Previous studies focused on outcomes after fresh embryo transfer, whereas this study investigated the influence of sperm DNA fragmentation index (DFI) on laboratory and clinical outcomes after frozen embryo transfer (FET). This retrospective study examined 381 couples using cleavage-stage FET. Sperm used for intracytoplasmic sperm injection (ICSI) or in vitro fertilization (IVF) underwent density gradient centrifugation and swim up processing. Sperm DFI had a negative correlation with sperm motility (r = -0.640, P < 0.01), sperm concentration (r = -0.289, P < 0.01), and fertilization rate of IVF cycles (r = -0.247, P < 0.01). Sperm DFI examined before and after density gradient centrifugation/swim up processing was markedly decreased after processing (17.1% vs 2.4%, P < 0.01; 65 randomly picked couples). Sperm progressive motility was significantly reduced in high DFI group compared with low DFI group for both IVF and ICSI (IVF: 46.9% ± 12.4% vs 38.5% ± 12.6%, respectively; ICSI: 37.6% ± 14.1% vs 22.3% ± 17.8%, respectively; both P < 0.01). The fertilization rate was significantly lower in high ( ≥25%) DFI group compared with low (<25%) DFI group using IVF (73.3% ± 23.9% vs 53.2% ± 33.6%, respectively; P < 0.01) but was equivalent in high and low DFI groups using ICSI. Embryonic development and clinical outcomes after FET were equivalent for low and high DFI groups using ICSI or IVF. In this study, sperm DFI did not provide sufficient information regarding embryo development or clinical outcomes for infertile couples using FET.