Study finds womb ageing may limit donor egg pregnancy success

Researchers from the IVIRMA Global Research Alliance at IVI Roma analyzed 2,760 single blastocyst transfers in 1,774 women treated between March 2021 and December 2024 in a study presented at the 42nd Annual Meeting of the European Society of Human Reproduction and Embryology in London. Donor eggs did not fully reset the reproductive clock, and age-related changes in the uterus and endometrium still tracked with poorer pregnancy outcomes.

The clearest break came at age 49. Among women 49 and older, clinical pregnancy rates fell to 42.6% from 54.0% in women aged 35 to 40, live birth rates dropped to 31.7% from 46.2%, and miscarriage rates rose to 37.6% from 24.2%. For women who transferred all available embryos, cumulative live birth rates declined from 80.0% in the youngest group to 62.5% in the 49-and-over group.

The study did not find a thinner uterine lining, but it did find age-related shifts in the lining’s structure. Endometrial thickness stayed similar across age groups, while the trilaminar endometrial pattern, which is generally associated with receptivity for embryo implantation, fell from 94.7% in women aged 35 to 40 to 81.0% in women aged 49 and older.

Researchers adjusted for embryo-, maternal- and paternal-related factors, and male-partner age did not significantly change the results. The analysis excluded women with known uterine abnormalities, women with a body mass index over 30, and couples with serious male-factor infertility, narrowing the focus to changes in the uterine environment.

Lead author Dr Beatrice Crestani said the findings support the idea that reproductive ageing is not only an ovarian issue. Professor Borut Kovacic, chair-elect of ESHRE, said the work points to a threshold associated with the beginning of loss of uterine function, while Professor Richard Anderson of the University of Edinburgh said fertility clinicians have long known that many age-related maternal risks in pregnancy are not removed by donor eggs.