Double vitrification-warming cycles coupled with one blastocyst biopsy do not affect the chance of live birth after an euploid blastocyst transfer: a propensity score matching study

To explore the effects of chromosomal aneuploidy screening and secondary vitrification-warming on the pregnancy and neonatal outcomes of non-biopsied, previously vitrified embryos. This retrospective cohort study included 963 single blastocyst transfer cycles between January 2018 and March 2023 that underwent one or two vitrification-warming and preimplantation genetic testing for aneuploidies (PGT-A). Propensity score matching was performed based on multiple baseline covariates, resulting in 351 conventional PGT-A cycles (single vitrification and single biopsy, SVSB group) and 197 thaw-biopsy-refreeze cycles (TBR group). The primary outcome was live birth rate, and secondary outcomes included biopsy parameters, clinical pregnancy outcomes, and neonatal outcomes. In the matched samples, clinical baseline levels and biopsy results were essentially identical in the SVSB group and TBR groups. The live birth rate following PGT-A on remaining frozen embryos was comparable to that of standard PGT-A (40.2 vs. 46.7, p = 0.138). No statistically significant differences were found in other pregnancy outcomes or neonatal outcomes. No significant obstetric complications were observed in either group, and only one infant in the TBR group died at 15 days of age. Performing PGT-A with a second vitrification-warming cycle on remaining embryos does not adversely affect pregnancy or neonatal outcomes.