Association between blastocyst morphology and pregnancy and perinatal outcomes following fresh and cryopreserved embryo transfer

PURPOSE: To assess the importance of each blastocyst morphological criteria with pregnancy and perinatal outcomes. METHODS: This single-center retrospective cohort study included blastocyst single embryo transfers (SET) performed between 1/2012–2/2018. Poisson regression was used to evaluate pregnancy outcomes following fresh and cryopreserved embryo transfer (CET) for association with blastocyst expansion, inner cell mass (ICM) quality, and trophectoderm (TE) quality. Among cycles resulting in live birth, associations with preterm birth, small for gestational age (SGA) and large for gestational age (LGA), were evaluated using logistic regression. RESULTS: A total of 1023 fresh and 1222 CET cycles were included, of which 465 (45.1%) fresh and 600 (48.5%) CET cycles resulted in singleton live birth. Clinical pregnancy rates increased with increasing expansion among fresh transfers (p for trend = 0.001) but not CET (p = 0.221), and with TE quality for both fresh and CET cycles (p = 0.005 and