Effect of blastocyst morphology and developmental speed on transfer strategy for grade “C” blastocyst in vitrified?warmed cycles

Abstract Background High-quality single blastocyst transfer (SBT) is increasingly recommended to patients because of its acceptable pregnancy outcomes and significantly reduced multiple rate compared double (DBT). However, there no consensus on whether this strategy also suitable for poor-quality blastocysts. Moreover, the effect development speed blastocysts has been controversial. Therefore, study aimed explore effects morphology neonatal during frozen embryo (FET) cycle ultimately provide references clinical strategies. Methods A total 2,038 FET cycles from 40 years old or less were included January 2014 December 2019 divided based number embryos transferred: D5-SBT ( n = 476), D5-DBT 365), D6-SBT 730), D6-DBT 467) groups. The SBT group was further morphology: D5-AC/BC 407), D5-CA/CB 69), D6-AC/BC 580), D6-CA /CB 150). Results When reach same speed, live birth rates DBT higher than those SBT. statistical difference in early miscarriage between AC/BC CA/CB stratified by (42.44 % vs. 20.82 %) (32.35 14.25 group. Furthermore, (AC/BC CA/CA group), D5 D6 Conclusions For blastocysts, can be with DBT. D6, improve outcomes. selecting inner cell mass “C” trophectoderm does not affect