Analysis of pregnancy outcomes of single top-quality blastocyst transfer developed from cleavage embryos with different grading

Abstract

Objective: To explore the clinical outcomes of top-quality blastocysts transfer developed from cleavage embryos with different grading and determine whether the cleavage stage embryo morphology grading should be taken into consideration when transferring the embryo at the blastocyst stage. Methods: A number of 3 059 cycles were included with single top-quality blastocyst transfer dating from January 2017 to May 2021 in Henan Provincial People's Hospital. According to the number of cleavage sphere and degree of fragmentation, all cleavage stage embryos were divided into three groups: top D3 embryo (8 cells, ≤5% fragments)-TB group, suboptimal D3 embryo (8 cells, 5%<fragments≤10%; 7 cells or 9 cells, ≤10%)-TB group, and normal D3 embryo-TB group. Univariate analysis, multivariate logistic regression analysis and threshold effect analysis were performed on the data. Results: The clinical pregnancy rates of top D3 embryo-TB group(1 326 cycles), suboptimal D3 embryo-TB group (830 cycles) and normal D3 embryo-TB group (903 cycles) were 69.53%, 70.12% and 66.67%, respectively (P>0.05); and the early abortion rate were 10.74%, 12.54% and 12.62%, respectively (P>0.05). After adjusting for confounders, logistic regression showed that no significant associations were found between cleavage stage embryo morphology grading and clinical pregnancy rate (suboptimal D3 embryo-TB group: OR=1.02, 95%CI: 0.76-1.38, P=0.879; normal D3 embryo-TB group: OR=0.84, 95%CI: 0.61-1.14, P=0.262) and early abortion rate (suboptimal D3 embryo-TB group: OR=1.18, 95%CI: 0.77-1.82, P=0.445; normal D3 embryo-TB group: OR=1.26, 95%CI: 0.81-1.98, P=0.309). The results of threshold effect analysis showed that when a single top-quality blastocysts was transferred, the effect of age on the clinical pregnancy rate showed a curve relationship, when the age was≥33 years old, the clinical pregnancy rate decreased significantly with age increased (OR=0.89, 95%CI: 0.83-0.95, P=0.007); and there was no significant change in early abortion rate (OR=1.01, 95%CI: 0.97-1.06, P=0.628). Conclusions: Cleavage stage embryo grading is not found to correlate with clinical outcomes in single top-quality blastcyst tranfer. Therefore, when considering blastocyst transfer, its morphology at blastocyst stage is more relevant. The effect of age on pregnancy outcomes of single blastocyst transfer should be considered.