Embryonic Arrest is more likely to Happen in Frozen-Thawed Embryo Transfers

Purpose: We mainly aimed to compare the incidence of embryonic arrest between fresh embryo and frozen-thawed embryo transfers.

Methods: This study included 4592 fresh embryo and 4461 frozen-thawed embryo transfers. In fresh embryo transfers, it included 3003 cleavage-stager embryo and 1589 blastocyst-stage embryo transfers. In frozen-thawed embryo transfers, it included 1626 cleavage-stager embryo and 2835 blastocyst-stage embryo transfers. Main clinical outcomes: embryonic arrest rate.

Results: Fresh embryo transfers had a lower embryonic arrest rate than frozen-thawed embryo transfers, with statistically significant difference (6.08 versus 7.20%; p=0.032). However, in cleavagestage embryo transfers, fresh group and frozen-thawed group had no significant difference in the embryonic arrest rate (6.59 versus
6.95%; p=0.644). We also observed that the embryonic arrest rate was no significant difference between cleavage-stage embryo and blastocyst-stage embryo transfers (6.72 versus 6.53%; p=0.722). More interestingly, single cleavage-stage embryo transfers had a higher embryonic arrest rate compared with single blastocyst-stage
embryo transfers (8.13 versus 4.67%; p=0.010).

Conclusions: Embryonic development is more likely to happen in frozen-thawed embryo transfers. Frozen-thawed embryo transfers might not be a superior choice to patients with prior embryonic arrest. Extended culture to blastocyst-stage might be a superior therapy to another fresh cycle in patients with prior embryonic arrest.