EMBRYOLOGISTS ARE MORE LIKELY TO CHOOSE EUPLOID EMBRYOS FOR TRANSFER: A PROSPECTIVE BLINDED NON-SELECTION TRIAL

Abstract

A number of morphologic parameters assessed using conventional microscopy or time-lapse imaging have been correlated with embryo euploidy. However, these parameters have not been validated in prospective studies. Similarly, it has not been established whether morphologic grading systems or other more subjective strategies utilized by embryologists help select euploid embryos over aneuploid ones. In this study, we tested the hypothesis that morphologic grading systems used in the embryology laboratory preferentially select euploid embryos. To test this hypothesis we conducted a prospective non-selection study where embryos were biopsied and underwent PGT-A, but embryologists, physicians, and patients were blinded to the PGT-A results until after the embryo transfer. This study design provided a unique opportunity to determine whether embryologists are more likely to choose euploid embryos for transfer. Women ages 35-42 undergoing their first IVF cycle with PGT-A were included. All embryos were cultured to the blastocyst stage. Embryo grading was performed using the modified Gardner blastocyst grading system, and embryos were selected for transfer based on morphology alone. Genetic testing results were withheld until after frozen embryo transfer was completed. The odds of selecting a euploid versus aneuploid embryo for transfer was calculated. Results were adjusted for patient age. 1,111 blastocysts became available for transfer from 156 patients. The median (IQR) number of embryos per patient was 6 (5-9). A total of 156 single embryo transfers were performed where embryos were selected by embryologists based on morphology. Of the transferred embryos, 129 were later found to be euploid and 27 were aneuploid. Euploid embryos were 1.9 times more likely to be selected for transfer compared to aneuploid embryos (OR 1.99 CI [1.27-3.12]; p=0.0026). When the data was analyzed based on age, euploid embryos were 2.79 times more likely to be chosen for transfer in the <35-year-old group (p=0.012) and 1.7 times more likely in the >35-year-old group (p=0.065), although we were not powered to detect the true association in the latter group. Embryo assessment utilizing morphologic grading preferentially selects euploid embryos for transfer.