Oocyte vitrification reduces blastocyst yield but preserves reproductive competence in advanced maternal age patients undergoing oocyte accumulation with PGT-A

Research question: Does oocyte vitrification affect embryological and reproductive outcomes in women of advanced maternal age undergoing oocyte accumulation for PGT-A? Design: Retrospective observational study (n = 122, mean age: 39.7 ± 2.7 years) undergoing IVF with oocyte accumulation for PGT-A. Each patient contributed vitrified‒warmed cohort (VW) and sibling fresh cohort (F) MII oocytes. The first oocyte cohort was vitrified after the first oocyte retrieval and warmed for insemination alongside fresh oocytes from the second oocyte retrieval. Trophectoderm biopsy and next-generation sequencing-based PGT-A were conducted at the blastocyst stage. Primary outcome was blastocyst formation rate per MII; secondary outcomes were euploidy rate, pregnancy and neonatal outcomes, from the proceeding frozen embryo transfer. Results: Vitrification significantly reduced blastulation rate per MII-allocated oocyte (24.6 ± 34.1% VW versus 44.2 ± 33.9% F; P < 0.0001). Despite lower blastocyst yield, euploidy rates per biopsied blastocyst were comparable (38.8% VW versus 38.0% F; P = 0.91) as were the aneuploidy types. Clinical pregnancy (40.9% VW versus 61.2% F, P = 0.11), miscarriage (11.1% VW versus 10.0% F, P = 0.92) and live birth rates (36.4% VW versus 55.1% F, P = 0.14) per single euploid embryo transfer did not differ. No differences were found in neonatal outcomes, including gestational age, birth weight and sex distribution. Conclusions: Oocyte vitrification does not affect euploidy rates or chance of live birth per euploid embryo transfer. The reduction in blastocyst yield observed in older patients indicates that this population should be appropriately counselled about the potential effect on embryo availability and cumulative outcomes.