LIVE BIRTH RATES ARE SIGNIFICANTLY DECREASED FOLLOWING TRANSFER OF A EUPLOID BLASTOCYST WITH DIRECT UNEQUAL CLEAVAGE

Abstract

Embryos can have direct unequal cleavage (DUC) during the first and/or second divisions. Although embryos with DUC have decreased blastulation rates, some develop into high quality euploid blastocysts. The objective of this study is to compare live birth (LB) rates following transfer of single frozen euploid blastocysts that either did or did not display DUC. This was a retrospective chart review of patients who underwent single frozen euploid blastocyst transfers from November 2018 to March 2020. Uninterrupted embryo culture was done in the Embryoscope up to 6 days post retrieval. Embryos were evaluated on day 2 for presence/absence of DUC and graded on day 5 or 6 according to the Gardner system. Blastocyst selection for frozen embryo transfer was based on euploidy status, developmental day, morphological score, and sex preference. Information regarding presence/absence of DUC was not accessed during blastocyst selection. Patient characteristics and LB rates were compared between the groups with and without DUC. Chi-square and Student’s t-tests were used for data analysis. A total of 114 single euploid blastocyst transfers were included, resulting in an overall LB rate per transfer of 63.2%. Twenty-two of the transferred blastocysts displayed DUC, whereas 92 did not. The overall LB rate in the DUC group was significantly lower than in the non-DUC group (31.8% vs 70.7%, p<0.01). Subgrouping blastocysts by developmental day and morphology showed significantly lower LB rates for day 6 and fair quality DUC blastocysts, compared with non-DUC blastocysts (18.2% vs 63.6%, p<0.05) (35.7% vs 70.6%, p<0.05). Live birth rates following single frozen euploid blastocyst transfer are significantly lower when blastocysts display DUC compared with blastocysts without DUC. When available, embryo division patterns should be considered when selecting a euploid blastocyst for frozen embryo transfer.