Women over 49 have lower chance of live birth, even with donor eggs

Uterine ageing affects the chances of pregnancy independently of egg quality, according to research presented at the 42nd Annual Meeting of the European Society of Human Reproduction and Embryology (ESHRE) in London.

Researchers from IVIRMA in Rome, Italy, examined data from donor egg cycles to separate the effects of ageing on egg quality from those on implantation and the uterine environment. They found that women over 49 had lower clinical pregnancy rates, lower live birth rates and higher rates of miscarriage compared to women aged 35-49.

'For many years, reproductive ageing has been seen primarily as an ovarian issue,' said lead author Dr Beatrice Crestani, who presented the research. However, beyond the age of 49 we observed lower live birth rates and higher miscarriage rates despite the use of donor eggs, suggesting that age-related changes in the uterine environment may also influence reproductive success.

Dr Crestani and her colleagues analysed data from 2760 embryo transfers in 1774 women aged 35 and over, which took place between 2021 and 2024. All embryos were created using donor eggs. They excluded data from women with known uterine abnormalities or BMI over 30, as well as couples with serious male factor infertility.

The transfer outcomes were stratified into four groups by recipient age (35-40, 41-45, 46-49 and over 49 years). Live birth rates were 46.2 percent per transfer in the youngest group, compared to 31.7 percent in the over 49s. The chance of a transfer resulting in miscarriage was 37.6 percent in the oldest cohort, compared with 24.2 percent in those aged 40 and under.

They also looked at the age of male partners whose sperm was used – as older women tend to have commensurately older partners – but found that did not have a significant effect.

Fertility practitioners have 'long been aware that many age-related maternal risks in pregnancy are not negated by [use of donor eggs],' Professor Richard Anderson, head of obstetrics and gynaecology at the University of Edinburgh, who was not involved in the study, told BioNews. 'However, this is a valuable study that analyses pregnancies from the use of egg donation to highlight that the uterus doesn't work so well in older women.'

Professor Borut Kovacic, chair-elect of ESHRE, said: 'In recent years, increasing research efforts have focused on understanding the processes that enable cross-talk between the embryo and the endometrium, marking the onset of implantation. This study identifies an age threshold associated with the beginning of loss of uterine function.'

However, Dr Crestani cautioned that: 'These findings should not discourage women from pursuing donor-oocyte treatment, because success rates remain meaningful even at advanced ages. However, patients should be counselled that donor eggs cannot completely eliminate the effects of reproductive ageing, particularly beyond 49 years.'