Cryopreservation of both male and female gametes leads to reduced embryo development and implantation potential

The objective of this study was to investigate the effect of oocyte and sperm cryopreservation on donated eggs submitted to intracytoplasmic sperm injection (ICSI) cycles. Medical charts of 122 oocyte recipients undergoing 152 oocyte recipient ICSI cycles, from 2017 to 2018, in a private university-affiliated in vitro fertilization (IVF) centre, were reviewed in this historical cohort study. Cycles were divided into four groups according to the gamete status: the FO/FS Group, recipients in which fresh oocytes were injected with fresh sperm (n = 19); the FO/CrS Group, recipients in which fresh oocytes were injected with cryopreserved sperm (n = 14); the CrO/FS Group, recipients in which cryopreserved oocytes were injected with fresh sperm (n = 85); and the CrO/CrS Group, recipients in which cryopreserved oocytes were injected with cryopreserved sperm (n = 34). Generalized mixed models fit by restricted maximum likelihood, followed by Bonferroni post hoc test for the comparison ofmeans amongst groups were used to investigate the effect of cryopreservation on recipient ICSI outcomes. The results were expressed as mean differences with 95% confidence intervals and P-values. The main outcome measure was the implantation rate. Normal day 3 cleavage speed, blastocyst development and implantation rates were significantly lower in the CrO/CrS Group compared with the FO/FS Group. In conclusion, embryo developmental competence and implantation potentialwere reduced when vitrified oocytes were injected with frozen sperm in an egg-sharing donation programme.