ABSTRACT
Objective To estimate the effect of blastocysts morphological score on pregnancy outcomes and neonate′s condition in vitrified-warmed single-blastocyst transfer cycles. Methods A retrospective analysis of 586 cycles of vitrified-warmed single-blastocyst transfer from Mar. 2010 to Feb.2016 was performed and the influ-ence of day of vitrification,inner cell mass(ICM)and trophectoderm(TE)scores on pregnancy outcomes and neo-nate′s condition were observed. Results There were no significant differences in clinical pregnancy rate,birth weight and sex ration of newborn between different vitrification day,ICM score and TE score.The day of vitrifica-tion and ICM score can significantly influence pregnancy loss rate,and were the two primary predictors of pregnan-cy loss rate. Vitrification day,ICM score and TE score exerted significant influence on live birth rate(P < 0.05) and TE score was the primary factor of live birth rate. Conclusions Day 5 vitrified blastocysts with higher quality of ICM and TE can provide high live birth rate and low pregnancy loss rate,but it could not predict the weight and gender of the newborn.