Clinical outcomes of frozen-thawed blastocysts from zygotes with no or one pronucleus for in vitro fertilization and intracytoplasmic sperm injection cycles

Abstract Purpose To investigate the clinical outcomes of in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycles using frozen-thawed blastocyst transfers derived from zygotes with no (0PN) or one pronucleus (1PN). Methods This retrospective study included 7084 0PN, 2238 1PN and 72266 two-pronuclear (2PN) embryos cultured into blastocyst stage from 19631 IVF and 12377 ICSI cycles between March 2018 and December 2021. Developmental potential and clinical outcomes of 0PN, 1PN and 2PN embryos were analyzed. A total of 290 0PN-derived, 92 1PN-derived and 1906 2PN-derived single frozen-thawed blastocyst transfers were performed. Chromosome analysis of 0PN-, 1PN- or 2PN-derived blastocysts used Infinium Asian Screening Array gene chip or next-generation sequencing. Results The available blastocyst rates of 0PN and 1PN embryos were significantly lower than those of 2PN embryos in both IVF and ICSI cycles. Single 0PN and 1PN blastocysts transferred in frozen-thawed cycles resulted in a similar clinical pregnancy rate, live birth rate and miscarriage rate compared with 2PN blastocysts, in both IVF and ICSI cycles. Genetic analysis showed that euploid rates of 0PN- and 1PN-derived blastocysts used for ICSI cycles were similar to that of 2PN-derived blastocysts. Conclusion Our study indicated that 0PN- and 1PN-derived blastocysts resulted in a similar CPR and LBR as 2PN-derived blastocysts. The 0PN- and 1PN-derived blastocysts from ICSI cycles can be transferred as well as those from IVF cycles when the number of 2PN-derived blastocysts is insufficient.