July 6, 2026

expert reaction to conference abstract from ESHRE on advanced maternal age independently affecting live birth and increasing miscarriage risk in donor oocyte cycles

A conference abstract presented at ESHRE looks at maternal age, live birth and miscarriage risk in donor oocyte cycles. 

Dr Norah Fogarty, Group Leader & Lecturer, King’s College London (KCL), said:

“Their claim that birth rates substantially decreased with advanced maternal age was on the basis of cumulative live birth rate — the probability of a live birth over multiple embryo transfers (as defined in this study). 

“Restricting cumulative live birth rate calculation to only patients who used all their available embryos (as stated in this abstract) introduces several specific problems. 

“A key drawback is that patients who get pregnant early usually stop before using all their embryos — so if a study only counts patients who used every embryo, it can leave out many of the best outcomes. This makes the “completers-only” group unrepresentative, since it may overrepresent people with poorer prognoses while excluding early successes. A fairer approach looks at all patients who started treatment, using statistical methods that account for the different reasons people stop (success, poor prognosis, or personal choice) rather than excluding anyone who didn’t use every embryo.

“This could be mitigated against by using an intention-to-treat cohort with survival analysis (Kaplan-Meier) and reporting why patients discontinued (success vs. medical advice vs. personal choice), would let researchers separate true uterine-aging effects from potential artifacts of the cumulative live birth rate calculation method.”

Dr Emma Lucas, Lecturer in Reproductive Medicine, University of Sheffield, said:

“The study has a high number of participants overall, which is a strength, although of course the number in the >49 age is comparatively small as this will represent only a subset of the patients receiving embryo transfers. It should also be noted that all the participants in this study are >35 years old, so we don’t have a comparison to younger patients.

“Without seeing the full paper, it is difficult to determine if there are other confounding factors to consider, but the authors do report adjusting for paternal factors (note that the paternal age also increased in the >49-year-old females), as well as embryo and maternal factors. It is not clear what the embryo factors might be, so we would need to see if there are differences in embryo quality between the groups, perhaps because of the paternal age increasing. We also don’t know the prior pregnancy history of the patients, which could impact the success of their treatment – we know for example that there is an increased risk of miscarriage with each prior loss. Hopefully this has been accounted for in the consideration of maternal factors.

“There is evidence to suggest that endometrial preparation protocols can influence miscarriage risk (including being presented in the same conference). The use of HRT cycles increased with age in this study, and although that should have been accounted for in the statistical analysis, without seeing the full paper we don’t know if there are variations within the patients in terms of the hormone regimen they were exposed to. The numbers within the >49 group might not support a subgroup analysis here.

“As noted by the authors, the pregnancy rates achieved in the >49y group are still good, and similar to the rate of natural conception at younger age. The key message shared by the authors is that while donor oocytes can mitigate some of the effects of maternal aging, probably due to improved embryo quality, the chance of achieving a successful pregnancy decreases with age and the likelihood of miscarriage does appear to increase. Notably, there are other risks of pregnancy with advanced maternal age that could influence the successful outcomes of any pregnancy that is achieved. Couples should be counselled about all these risks during consultations with their clinic.

“In order to really understand the mechanisms underpinning these findings, it would be necessary to examine the uterine lining at the functional and molecular level, for example by investigating hormone responsiveness and receptivity to embryos of both good and poor quality.”

Dr Priya Bhide, Clinical Reader in Obstetrics and Gynaecology, Queen Mary University of London (QMUL), said:

“This study provides very useful information for patients and those seeking treatment with donor eggs. It is a conference abstract which provides a summary of the study design and results. The full manuscript with data analysis will provide greater detail for scientific scrutiny and the press release accurately reflects the science.

“Comparable data have been reported in the literature. The findings are consistent with previous studies, provide external validation, and support the generalisability of these results.

“Adjustment for confounders is crucial in the cohort design used in this study, given the inherent risk of selection bias among included participants. While the abstract notes that analyses were adjusted for confounders, the full manuscript is required to evaluate their influence on the reported outcomes adequately. The study demonstrates association rather than causation.”

Prof Ying Cheong, Professor of Reproductive Medicine and Honorary Consultant in Reproductive Medicine and Surgery, University of Southampton, said:

“This is a well-designed study because it uses donor eggs to strip out egg quality and isolate the uterus itself as a factor in age-related infertility, something that’s been hard to study directly until now. The finding that live birth rates fall and miscarriage rates roughly double after 49, even with young donor eggs, is a genuinely useful clinical signal.

“But two important caveats. First, it’s retrospective, so it shows an association between age and outcome, not proof that uterine ageing is the cause; other differences between older and younger patients could be playing a role. Second, it’s non-mechanistic: we know something changes in the womb lining with age, but not why, so it’s too early to talk about testing for or treating ‘uterine age’. It’s also still a conference abstract, not yet a peer-reviewed paper, so full scrutiny of the methods isn’t possible yet.

“This shouldn’t discourage anyone. Donor-egg success rates remain good well into the late forties. But it does challenge the assumption that donor eggs fully reset the reproductive clock, and points to uterine ageing, amongst many uterine related conditions, as an area needing more mechanistic research to understand what’s actually driving these outcomes.”

‘Advanced maternal age independently affects live birth and increases miscarriage risk in donor oocyte cycles’ by B. Crestani et al. was presented at ESHRE. 00:01 UK Time Monday the 6th of July 2026. 

Declared interests

Dr Norah Fogarty:  “No DOI to declare here.”

Dr Emma Lucas: “I have no industry funding to declare. 

I am employed by the University of Sheffield and hold an honorary appointment at the University of Warwick. 

I have research funding from the Academy of Medical Sciences. 

I am Trustee and Treasurer of the Society for Reproduction and Fertility. 

I am a named co-inventor on patents relating to endometrial function testing.”

Dr Priya Bhide: “I have no DOI.”

Prof Ying Cheong: “No COI”