Uterine ageing may limit donor egg IVF outcomes after 49

IVF.net Newsdesk

10 July 2026

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A new study presented at the 42nd Annual Meeting of ESHRE has added important clinical evidence to a long-standing question in reproductive medicine: when donor eggs are used, how much does the age of the uterus still matter?

For many years, reproductive ageing has been discussed largely in terms of oocyte quality. This is understandable. Oocyte aneuploidy, reduced developmental competence and declining ovarian reserve are major contributors to lower fertility with increasing maternal age. Donor-oocyte treatment is therefore often viewed as a way to bypass the biological effects of ovarian ageing.

The new study, led by researchers from the IVIRMA Global Research Alliance at IVI Roma, suggests that this picture is more complex. By analysing donor-oocyte cycles, where embryo potential is less directly tied to the recipient’s own oocyte age, the researchers were able to look more closely at the contribution of recipient age and the uterine environment.

The analysis included 2,760 single blastocyst transfers in 1,774 women undergoing donor-oocyte treatment between March 2021 and December 2024. Outcomes were compared across four recipient age groups: 35 to 40, 41 to 45, 46 to 49 and 49 years or older. The study assessed clinical pregnancy rates, live birth rates, miscarriage rates and endometrial features, while adjusting for embryo, maternal and paternal factors.

The most clinically relevant finding was the identification of 49 years as a threshold beyond which outcomes appeared to decline despite the use of donor eggs. Clinical pregnancy rates decreased from 54.0% in recipients aged 35 to 40 to 42.6% in those aged 49 and over. Live birth rates fell from 46.2% to 31.7% across the same age comparison. Miscarriage rates increased from 24.2% to 37.6%.

The study also reported a reduction in cumulative live birth rates when all available embryos were transferred. Among recipients aged 35 to 40, the cumulative live birth rate was 80.0%. In recipients aged 49 and over, it was 62.5%. These findings suggest that donor eggs can substantially improve reproductive potential in older patients, but may not completely remove the influence of recipient age.

A particularly interesting aspect of the study was its assessment of the endometrium. Endometrial thickness remained similar across age groups, but the proportion of women with a trilaminar endometrial pattern declined with age. This pattern, often associated with endometrial receptivity, was present in 94.7% of women aged 35 to 40 compared with 81.0% of women aged 49 and over.

This distinction is important. Endometrial thickness is widely measured in clinical practice, but thickness alone may not fully capture the functional state of the uterine environment. A uterus that appears adequate by thickness may still show age-related changes in vascular function, immune signalling, hormonal response, stromal behaviour or molecular receptivity.

The findings do not suggest that donor-oocyte IVF is ineffective in older recipients. On the contrary, pregnancy and live birth outcomes remained clinically meaningful even in women at advanced reproductive ages. However, the data support more nuanced counselling. Donor eggs can address the problem of oocyte ageing, but they may not fully reset reproductive ageing if the uterine environment has also changed.

For IVF clinics and laboratories, the study reinforces the importance of separating embryo-related and uterine-related contributors to treatment outcome. A high-quality donor-oocyte blastocyst may still implant and develop within a biological environment influenced by recipient age. This has implications for patient counselling, protocol selection and future research into endometrial assessment.

The next step will be to understand what “uterine biological age” really means in clinical terms. The study points toward the need for better biomarkers that go beyond age, endometrial thickness and visual pattern. Future work may help identify which patients have preserved uterine receptivity at older ages and which may have an increased risk of miscarriage or reduced live birth despite good embryo quality.

For now, this study offers a useful and balanced message. Donor-oocyte treatment remains a powerful option for patients affected by ovarian ageing. At the same time, reproductive ageing should not be viewed as exclusively ovarian. After 49, uterine and endometrial ageing may become increasingly relevant to the chance of live birth.

Sources

6 July 2026. ESHRE