O-015 Advanced paternal age affects miscarriage and live birth outcomes following the first transfer in oocyte donation cycles

Study question Does advanced paternal age affect miscarriage and/or live birth outcomes following the first transfer in oocyte donation cycles? Summary answer Advanced paternal age (>45 years old) increases miscarriage rates and decreases live birth rates following the first transfer in oocyte donation cycles. What is known already Donor oocyte cycles are becoming a common strategy for addressing female age-related infertility, offering high success rates (∼60% ongoing pregnancies) attributed to superior oocyte quality. However, male age-related effects on the success of ART have received less attention. In autologous cycles, advanced paternal age has been associated with poor clinical outcomes. However, disentangling its effects from female factors remains challenging. Oocyte donation cycles offer a useful model for studying the impact of male factors on ART outcomes, eliminating biases related to female age and underlying diagnoses. Study design, size, duration Multi-center, retrospective study of 1,712 first oocyte donation cycles performed between January 2019 and December 2023, across six IVF centers. Only ICSI cycles with fresh donor oocytes, inseminated with frozen partner sperm were included. Only the first single blastocyst transfers (fresh or frozen) were considered. Cycles with abnormal male karyotypes, sperm obtained from testicular biopsy, donor sperm, frozen oocytes, in-vitro matured oocytes or preimplantation genetic testing (PGT) were excluded. Participants/materials, setting, methods Paternal ages were categorized in two groups: ≤45 years old and >45 years old (advanced paternal age, APA). We assessed fertilization rates, the number of usable blastocysts and blastocyst utilization rate. Clinical outcomes included clinical pregnancy, miscarriage and live birth rates. P < 0.05 was considered statistically significant after Fisher’s exact test and a multivariate logistic analysis adjusting for recipient and oocyte age, number of mature (MII) oocytes injected and fresh/frozen embryo transfer. Main results and the role of chance Within the cohort of 1,712 patients who underwent a first oocyte donation cycle, the mean recipient age (±SD) was 43.3 (±4.1) years, the mean oocyte donor age (±SD) was 26.1 (±4.1) years, and the mean paternal age (±SD) was 43.5 (±6.3). In the ≤45 paternal age group (n = 1066), the mean paternal age (±SD) was 39.8 (±4,0) years, while in the APA group (n = 646), it was 49.6 (±4.1). No differences were observed in recipient age, oocyte donor age, number of oocytes fertilized or number of blastocysts obtained among paternal age groups. Interestingly, miscarriage rate was 23.8% (71/298) in the APA group and 16.3% (85/522) in the ≤45 years old group. The differences were significantly different (p = 0.006). Consequently, the live birth rate was also reduced 35.1% APA vs 41.0%, ≤45 years old (227/646 vs 437/1066; p = 0,009). These results were further confirmed in the adjusted analysis, where APA remained significantly associated with a higher miscarriage rate (OR = 1.61, [95%CI: 1.10-2.35], p = 0.014) and a lower live birth rate (OR = 0.77, [95%CI: 0.62–0.96], p = 0.022). Limitations, reasons for caution This study is limited by its retrospective nature. No data on the chromosomal status of the embryos was available. Caution is warranted when generalizing results to different embryo transfer strategies or other patient populations. Wider implications of the findings Our results indicate that paternal age can affect clinical outcomes in oocyte donation cycles. If confirmed in a larger cohort of patients, these results would suggest considering patient counseling in relation to APA when delaying childbearing. Trial registration number No