Recipient age and reproductive outcomes in donor oocyte cycles: exploring the potential contribution of uterine aging

To investigate whether uterine aging independently affects reproductive outcomes in oocyte donation cycles and to evaluate reproductive outcomes across increasing recipient age groups.

A retrospective cohort study includes 1774 women undergoing 2760 single blastocyst transfers with donor oocytes (March 2021-December 2024). Transfers were stratified by age: 35-40, 41-45, 46-49, and > 49 years. Multivariable logistic regression was adjusted for BMI, embryo quality, endometrial parameters, sperm characteristics, paternal age, number of inseminated oocytes, and PGT-A use. Uncensored and exploratory censored Kaplan-Meier analyses estimated cumulative live birth rates (CLBR).

Live birth rates declined progressively with advancing recipient age. Women aged > 49 years had significantly lower live birth rates (OR 0.62, 95% CI 0.41-0.93, p = 0.02) and higher miscarriage risk (OR 2.07, 95% CI 1.16-3.69, p = 0.01). CLBR decreased from 80% (35-40 years) to 62.5% (> 49 years) in uncensored analysis (p < 0.0001). The prevalence of trilaminar endometrium significantly declined in women ≥ 46 (p < 0.0001), while endometrial thickness remained comparable. Although advanced paternal age was associated with reduced fertilization and poorer embryo quality (p < 0.0001), it was not associated with implantation, live birth, or miscarriage rates in the subgroup of recipients aged > 49 years.

A clinically significant decline in live birth occurs in recipients aged > 49 years, suggesting a late-onset uterine aging effect. These findings may help guide counseling and risk assessment in women of advanced maternal age.