Effect of prolonged oocyte cryopreservation >10 years on reproductive outcomes – a systematic review and meta-analysis

Oocyte cryopreservation is essential for fertility preservation, yet the impact of prolonged storage on cryosurvival, embryological, and pregnancy outcomes remains unclear.A systematic review and meta-analysis of 20 studies (2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019)(2020)(2021)(2022)(2023) from MEDLINE, Embase, and Cochrane databases included 11,726 patients.Nine large studies (mean storage 3.79 years) were compared to 11 case reports (mean storage 10.2 years) to assess the impact of longer storage durations, as none of the large studies had 10 years of storage.In large studies, cryosurvival was 81%, fertilization 72%, and blastulation 42%.Per embryo transferred (n = 10,460), implantation, clinical pregnancy, and live birth rates were 35%, 40%, and 28% respectively.Case reports showed comparable cryosurvival (76%), fertilization (76%), and blastulation (36%), with all pregnancy outcomes exceeding 49%.A sub-analysis of the case reports stratified by cryostorage duration compared outcomes for 10 years (n = 11, mean 12.86 years) versus <10 years (n = 5, mean 4.27 years) showed similar cryosurvival (74% vs. 81%), lower fertilization (69% vs. 91%, p = 0.038), comparable blastulation (37% vs. 33%), and higher, though non-significant, clinical pregnancy and live birth rates (61% vs. 33%).Available evidence, predominantly from case reports, suggests prolonged oocyte storage does not compromise reproductive outcomes, though large prospective studies are needed.