Purpose: To provide clinicians with data showing the benefits of transferring a single blastocyst in frozen embryo transfer (FET) cycles so that they may counsel their patients accordingly.
Methods: This is a closed cohort study of 678 FET cycles occurring between January 2011 and December 2017 in a private IVF laboratory and associated physicians' practice. Patients included in the analysis were less than 38 years of age at oocyte collection, had at least two vitrified blastocysts, and were undergoing their first autologous FET cycle. The patients were categorized into four groups after they had chosen either elective single-embryo transfer (eSET) or double-embryo transfer (eDET). Outcomes for eSET and eDET were compared within groups of patients having freeze-all IVF cycles (PGT-A patient vs. non-PGT-A patient) and fresh IVF transfer groups (negative outcome vs. pregnant/delivered in fresh cycle). Main outcome measures of the study were live birth, multiple pregnancy, and implantation rates.
Results: There were no statistically significant differences observed in live birth rates for eSET (54-62%) vs. eDET (54-66%) (P = 0.696-1.000) in the four patient groups evaluated. Multiple pregnancy rates were significantly decreased in all eSET groups (0-3%), compared with eDET groups (24-65%) (P = 0.0001-0.037).
Conclusions: This data shows that transfer of a single vitrified-warmed blastocyst maintains live birth rates, while decreasing multiple pregnancies, and may become more acceptable to physicians and patients.
Keywords: FET; Frozen embryo transfer; IVF; Single-embryo transfer; eSET.