Effect of Blastocyst Morphology and Developmental Rate on Euploidy and Live Birth Rates in PGT-A Cycles: A Retrospective Cohort Study

This study was to evaluate the relationship between morphology or developmental rate of blastocysts and ploidy status in preimplantation genetic testing for aneuploidy (PGT-A) cycles, or live birth rates in single euploid frozen-thawed embryo transfer (FET) cycles. We focused on infertile patients who underwent PGT-A procedures, following with single euploid FET cycles in the assisted reproduction center from January 2016 to December 2022. Blastocysts were categorized for biopsy, and euploid embryos would be selected for transfer. Multivariate logistic regression was used to assess the effects of blastocoel expansion degree, inner cell mass (ICM) and trophectoderm (TE) grades and developmental stage (Day 5, 6 and 7) on euploidy and live birth rates. A total of 4172 blastocysts from 941 PGT-A cycles were included. Expansion 4 were associated with lower euploidy rate than expansion 5 (P = 0.011) and 6 (P = 0.001). Better ICM (P < 0.05 for A compared to B grade) increased blastocyst euploidy. Euploidy rate was significantly associated with A grade TE (P < 0.001). However, no relationship existed between blastocyst euploidy and developmental rate. Furthermore, live birth rates had no significant effect on most of morphological parameters in euploidy blastocyst FET cycles, only A grade TE was shown higher live birth rate than C grade (P = 0.024). The rate of euploidy in morphologically poor blastocysts is low in the cohort, but the developmental rate does not associate with euploidy. Moreover, only TE grades take association with live birth rates, when the single euploidy blastocyst was transplanted.