Blastocyst morphology grade does not influence the abortion rate of frozen-thawed single blastocyst transfer

Abstract

To estimate the effect of inner cell mass (ICM) morphology grade and trophectoderm (TE) morphology grade on abortion and live birth in frozen-thawed single blastocyst transfers (SBT). Retrospective study. Outcome was evaluated by abortion rate (AR), defined as the number of abortion per clinical pregnancy and live birth rate(LBR),defined as the live birth per embryo transfer(ET). This study included all the patients who received frozen-thawed single blastocyst transfer (n=374) at our center between Dec 2010 and May 2013.The morphological evaluation of blastocysts was performed according to the Gardner and Schoolcraft grading system and included three different parameters: expansion and hatching (EH) stage, ICM grade and TE grade. For blastocysts with grade of 3BB or better were frozen. The mean age of patients was not significantly different between the groups (ICM grade A group vs. ICM grade B group, 31.9 vs.32.3 years and TE grade A group vs. TE grade B group, 31.6 vs. 32.4 years). AR and LBR were compared between the groups using chi square Test. The AR of frozen-thawed SBT cycles was 23.4%(26/111) vs. 24.0%(18/75) for ICM grade A vs. B groups (P=0.927) and 21.7% (20/92) vs. 25.5%(24/94) for TE grade A vs. B groups (P=0.542), neither of which did not differ significantly. The corresponding LBR of frozen-thawed SBT cycles was 47.0%(85/181) vs. 29.5%(57/193) for ICM grade A vs. B groups (P<0.001) and 51.4%(72/140) vs. 29.9%(72/234) for TE grade A vs. B groups (P<0.001), both of which were statistically significant. Our study demonstrated that higher live birth rate was obtained after transfer with AA grade blastocyst compared with BB grade blastoycst. However, the abortion rate did not differ with different morphology grade, indicating the morphology evaluation of the blastocyst would only predict the implantation potential of the blastocyst but not the ongoing pregnancy.