Influencing factors of live birth in vitrified oocyte donation cycles: A retrospective cohort study

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Objective To evaluate the live birth rate (LBR) of assisted reproductive technology (ART) treatment using vitrified donated oocytes in China and to investigate the influencing factors on live birth outcomes. Methods This retrospective cohort included 377 infertility women who underwent ART with vitrified donated oocytes at a large reproductive center in China between January, 2015 and June, 2024. Among them, 369 women underwent embryo transfer. The primary outcome was LBR after the first transfer. The multivariable Logistic regression model were employed to estimate the influencing factors of live birth outcomes. Results The LBR of the first transfer was 51.5% (190/369). Advanced recipient age (adjusted odds ratio [aOR]: 0.92, 95% CI: 0.85-0.98, P = 0.015) and a history of previous poor oocyte/embryo quality (OR: 0.38; 95% CI: 0.18-0.75; P = 0.007) were associated with a reduced LBR. The cumulative live birth rate (CLBR) per initiated oocyte donation cycle was 58.5% (216/369). Advanced recipient age and a history of previous poor oocyte/embryo quality were associated with a reduced CLBR, and an increased number of day-3 usable embryos significantly improved the CLBR (OR: 1.47; 95% CI: 1.26-1.73; P = 0.000). Prolonged oocyte cryopreservation duration exerts no adverse impact on laboratory or clinical outcomes. Increased thawed oocytes hardly boost LBRs but raise surplus embryos. Conclusions Advanced recipient age and a history of poor oocyte/embryo quality are significant factors reducing LBRs in ART treatment with vitrified donated oocytes. Long-term oocyte cryopreservation is safe, and rational batch oocyte allocation is recommended.