Li M, Huang J, Zhuang X, et al. - Via this cohort study, researchers sought to determine the obstetric and neonatal outcomes after the transfer of vitrified-warmed single blastocysts developing from nonpronuclear (0PN) and monopronuclear (1PN) zygotes. monopronuclear (1PN). They retrospectively analyzed 435 0PN and 281 1PN vitrified-warmed single blastocyst transfers, and 151 0PN and 75 1PN singletons, compared with 13,167 two-pronuclear (2PN) vitrified-warmed single blastocyst transfers and 4,559 2PN singletons, respectively. Based on outcomes, they emphasize prioritizing the transfer of 2PN blastocysts in lieu of a higher abortion rate (AR) and a lower live birth rate (LBR) after 1PN blastocyst transfers and a higher birthweight after 0PN blastocyst transfers when compared with 2PN blastocyst transfers. The data highlight the necessity for concern regarding the safety of 1PN and 0PN embryo transfers.