Clinical and pregnancy outcomes of double and single blastocyst transfers related with morphological grades in vitrified-warmed embryo transfer

Abstract

Objective: To evaluate clinical and pregnancy outcomes of double and single blastocyst transfers related with morphological grades in vitrified-warmed embryo transfer.

Materials and methods: In a retrospective cohort analysis, data were assessed from women who underwent vitrified-warmed blastocyst transfers (VBT) at CHA Gangnam Medical Center between 2014 and 2015. All VBT cycles were categorized into three groups according to blastocyst quality: GG (double good blastocysts transfer), GP (one good and one poor blastocyst transfer), and GS (single good blastocyst transfer). Blastocysts were graded morphologically and ⩾3BB grade was considered good quality.

Results: There were 628 transfers in group GG, 401 transfers in group GP, and 277 transfers in group GS. Both clinical pregnancy rate (CPR) and live birth rate (LBR) were the highest in group GG (CPR 65.9%, LBR 55.3%, p < 0.001), but not significantly different between group GP and GS. Multiple pregnancy rates increased significantly in the following order: GS (1.4%), GP (13.5%), and GG (25.6%). Single LBR was the highest in group GS (38.6%, p < 0.001).

Conclusion: As an effective VBT, especially for reducing multiple pregnancy and increasing single live birth, single good blastocyst transfer may be recommended rather than any double blastocyst transfer methods. Moreover, transferring a good and a poor blastocyst simultaneously should be avoided.

Keywords: Blastocyst; Embryo grade; Embryo morphology; Pregnancy outcome; Vitrified-warmed embryo transfer.