Objective A higher oocyte yield is generally associated with improved outcomes in assisted reproductive technology (ART). Vitrification enables the accumulation of oocytes, zygotes, or embryos across multiple cycles, offering a potential strategy to enhance success in women with diminished ovarian reserve (DOR), who typically produce few oocytes per stimulation cycle. Among accumulation approaches, vitrified zygote banking remains understudied regarding its clinical efficacy and cost-effectiveness. This study aimed to evaluate clinical pregnancy rates, live birth rates, and treatment costs associated with vitrified zygote banking in women with DOR. Materials and methods This retrospective cohort study included 122 women with DOR (POSEIDON Groups 3 and 4) who underwent controlled ovarian stimulation (COS) and embryo transfer (ET) using banked vitrified two-pronuclear (2 PN) zygotes between June 2019 and December 2022. Primary outcomes were clinical pregnancy and live birth rates; secondary outcomes included treatment costs per patient and per transfer cycle. Outcomes were also compared by maternal age and against a historical cohort from the same institution. Results The overall clinical pregnancy rate per embryo transfer cycle was 22. 3%, and the live birth rate was 14. 5%. Women aged <40 years achieved significantly higher live birth (24. 1% vs. 8. 3%, p = 0. 027) and implantation rates (16. 8% vs. 7. 5%, p = 0. 019) compared to those aged ≥40 years, while clinical pregnancy rates were comparable between age groups. Zygote banking was associated with higher treatment costs per patient and per transfer cycle than a simulated fresh transfer model (all p < 0. 05). The estimated cost per live birth was lower in women aged <40 years (NT891, 154) than in those aged ≥40 years (NT2, 814, 143). Patients achieving live birth incurred higher mean treatment costs than those without live birth, although this difference did not reach statistical significance (p = 0. 056). Compared to a historical fresh transfer cohort, clinical pregnancy and live birth outcomes with zygote banking were comparable in women aged <40 years, with a higher clinical pregnancy rate observed in those aged ≥40 years (p = 0. 018). Conclusions Vitrified zygote banking yielded clinical pregnancy and live birth outcomes comparable to conventional fresh embryo transfer, though differences in study design limit direct comparison. While associated with higher treatment costs, zygote banking may provide additional flexibility in embryo selection and transfer timing. Further prospective studies are needed to validate its clinical and economic utility.
Huang et al. (Fri,) studied this question.