Live Birth Rate After Transfer of a Single Euploid Blastocyst With and Without a Multinucleated Embryo

Background: Multinucleation, a deviation from typical embryonic development, is frequently observed during in vitro fertilization (IVF) cycles. The relationship between multinucleation at the two-cell stage (2MN), chromosomal status, and live birth remains poorly defined. Objective: This study aimed to investigate whether 2MN is associated with chromosomal status, determined by preimplantation genetic testing for aneuploidy (PGT-A), and live birth outcomes following single embryo transfer. Methods: This prospective study, conducted from January 2023 to December 2023, included 152 patients undergoing IVF. Oocytes were cultured and monitored in a time-lapse system, and blastocysts were analyzed by PGT-A. Results: 23.3% of embryos exhibited 2MN. Euploidy rates were significantly lower in the 2MN group (36.0%) compared to the non-multinucleation group (46.3%) (p < 0.05), and mosaicism was significantly more frequent in the 2MN group (42.6% vs. 31.1%, p < 0.05). However, live birth rates following euploid embryo transfer did not differ significantly between the non-multinucleation group (61.8%) and the multinucleation group (62.3%) (p > 0.05). Conclusions: While 2MN is associated with reduced euploidy rates and increased mosaicism, euploid embryos with early multinucleation have comparable live birth rates to non-multinucleated embryos. A limitation of the study was the relatively small sample size for the live birth outcome subgroup.