Preimplantation genetic testing for aneuploidy 'rescues' poor-quality blastocysts and increases embryo availability for transfer: a 9-year single centre analysis

Does preimplantation genetic testing for aneuploidy (PGT-A) and the transfer of euploid poor-quality blastocysts (PQB) reduce the number of transfers needed to achieve live births compared with the transfer of their untested counterparts? Single-centre retrospective cohort study conducted between 2015 and 2024 (PGT-A blastocysts: n = 7332 from 2258 cycles; n = 1344). Transfer outcomes were analysed for a subset of 74 cycles involving tested PQB and compared with 192 cycles involving untested PQB during the same period. High-quality blastocysts (AA, AB, BA and BB) were most likely to be euploid (P < 2.2e-16), whereas PQB (CC, DC, CD and DD) were more likely to be aneuploid (P < 2.2e-16). Embryos that reached the blastocyst stage by day 5 had a higher likelihood of being euploid. Among transferred PQB, PGT-A did not significantly affect the pregnancy rate (33.3% versus 23.4%); however, the miscarriage rate was significantly lower in the PGT-A-tested group (13.6% versus 51.2%, P = 0.003). The number of live births was higher in the PGT-A group (26.4 % versus 11.1%, P = 0.004) and with the transfer of day-5 frozen blastocysts. Live births were observed from blastocysts with the poorest expansion and morphology scores. No significant differences were observed in gestational age or birth weight between the PGT-A and untested groups. A clinically relevant proportion of PQB are euploid, PQB can result in live births and euploid transfer is associated with lower miscarriage rates. In combination, this suggests that PQB should not be routinely discarded, particularly if they are prior-tested using PGT-A.