Women aged 49 and above are significantly less likely to achieve a successful pregnancy through fertility treatment, even when using eggs donated by younger women, according to new research that challenges long-held assumptions about reproductive ageing.
The study, which analysed 1,774 women undergoing in vitro fertilisation (IVF) with donor eggs, found that while donor eggs improve the chances of conception, they do not completely offset the effects of ageing on the uterus.
Researchers reported that women aged between 35 and 40 had a 54 per cent chance of becoming pregnant following IVF with donor eggs, compared with about 43 per cent among women aged 49 and older. Live birth rates also declined from 46 per cent to 32 per cent, while miscarriage rates rose from 24 per cent to 38 per cent in the older age group.
Lead researcher Dr Beatrice Crestani of an assisted reproduction medical institute in Italy said the findings suggest reproductive ageing extends beyond the ovaries.
“For many years, reproductive ageing has largely been viewed as an ovarian issue, with the assumption that replacing older eggs with younger donor eggs effectively resets the reproductive clock. Our findings suggest the picture is more complex,” she said.
According to the researchers, age-related changes in the endometrium — the lining of the womb where an embryo implants — may help explain the reduced success rates. Although the thickness of the womb lining appeared similar across age groups, its overall condition declined with age.
The researchers believe future studies could lead to ways of predicting, preventing or improving age-related changes in the womb, potentially enhancing fertility treatment outcomes for older women.
Despite the findings, Dr Crestani stressed that women should not be discouraged from pursuing donor egg treatment.
“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 the age of 49,” she said.
The study also found that when all available embryos were transferred, cumulative live birth rates were around 80 per cent for women aged 35 to 40, compared with 62.5 per cent among women aged 49 or older.
The findings resonate with the experience of television broadcaster Sharon Marshall, who underwent six years of IVF treatment before giving birth to her daughter at the age of 46 after seven treatment cycles.
Marshall said public attention often focuses on celebrities who have children later in life without highlighting the emotional and physical challenges many women endure.
“We look at celebrities who have given birth in their late 40s and early 50s and celebrate them. We don’t know what they have been through,” she said, adding that repeated IVF attempts took a significant toll on her physical and mental wellbeing.
She welcomed the study, saying women deserve honest information about the realities of trying to conceive at an older age.
Experts cautioned that fertility and uterine health vary from person to person, and the age of 49 should not be viewed as an absolute cut-off. Instead, they said the findings provide valuable evidence for counselling patients and guiding future research into uterine ageing.
Professor Borut Kovacic, Chair-elect of the European Society of Human Reproduction and Embryology (ESHRE), said the research offers an important foundation for understanding how the womb interacts with an implanting embryo and may help identify biomarkers associated with uterine ageing.
Dr Ippokratis Sarris, Chair-elect of the British Fertility Society, also called for further research, noting that pregnancies at older ages carry additional health risks and require comprehensive medical assessment and counselling.
The findings were presented at the European Society of Human Reproduction and Embryology annual meeting and have been published in a medical journal.
(BBC News)