Frozen blastocyst embryo transfer vs. frozen cleavage-stage embryo transfer in couples with recurrent implantation failure: a cohort study

Abstract

The objective of this prospective cohort study was to investigate whether cryopreservation of cleavage or blastocyst stage embryos improves <i>in vitro</i> fertilization outcomes in recurrent implantation failure (RIF) patients. The study comprised 575 patients who were allocated to receive either single frozen/thawed blastocyst-stage transfer (SBT) or frozen/thawed double-cleavage-stage embryo transfer (DET). The clinical pregnancy rate, implantation rate, and ongoing pregnancy rate were higher in the SBT group compared with the DET group (41.15% vs. 27.11%, <i>p</i> < 0.001; 41.15% vs. 19.28%, <i>p</i> < 0.001; 40.03% vs. 25.9%, <i>p</i> < 0.001), but the miscarriage rate did not differ between the two groups. It was concluded that frozen/thawed SBT could be a preferred strategy for RIF patients.