Older women face lower chance of fertility treatment working, even with donor eggs, study finds

IVF success declines with age even when women use young donor eggs, with a marked fall from around 49, research suggests.

The findings challenge the idea that donor eggs can fully “reset” the reproductive clock, although researchers said they should not discourage older couples from trying.

Dr Beatrice Crestani, from an assisted reproduction medical institute in Italy, said reproductive ageing had traditionally been seen mainly as an issue involving the ovaries.

She said replacing older eggs with younger donor eggs was often believed to “reset” the reproductive clock.

Dr Crestani added: “Our findings suggest the picture is more complex.”

The study followed 1,774 women undergoing in vitro fertilisation, or IVF, using donated eggs. IVF involves fertilising an egg in a laboratory before transferring an embryo to the womb.

Women in their mid to late 30s had a 54 per cent chance of becoming pregnant after treatment, compared with around 43 per cent among those aged 49 or older.

Live birth rates fell from 46 per cent to 32 per cent, while miscarriage rates rose from 24 per cent to 38 per cent.

Women aged 49 and older had twice the risk of miscarriage compared with those aged 35 to 40.

Researchers believe changes to the endometrium with age may help explain the difference. The endometrium is the lining of the womb where a fertilised egg or embryo implants and grows.

Although the thickness of the womb lining was similar across the age groups, its condition declined with age.

Researchers said future work might find ways to predict, prevent or improve uterine ageing.

Dr Crestani said: “These findings should not discourage women from pursuing donor-egg 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.”

Among women who transferred all their available embryos, the live birth rate was around 80 per cent for those aged 35 to 40 and 62.5 per cent for those aged 49 or older.

Experts stressed that the health of the womb and ovaries differs between women.

There is no legal upper age limit for IVF in the UK, unlike some European countries. Greece has an upper limit of 54.

Women in the UK can donate or share their eggs up to the age of 36.

Regulators ask private UK clinics to assess the welfare of any resulting child and whether the recipient can safely carry a pregnancy.

NHS guidelines recommend offering three IVF cycles to women up to the age of 40 and one cycle to women up to the age of 42.

Patients using donor eggs usually have to fund that part of the treatment themselves.

People conceived using sperm, eggs or embryos from donors registered after 1 April 2005 can request identifying information about their biological donor parent once they turn 18.

The findings are being presented at the European Society of Human Reproduction and Embryology.

Professor Borut Kovacic, chair-elect of the society, said researchers were trying to better understand the “cross-talk” between an implanting embryo and the womb lining. This refers to the biological signals exchanged during implantation.

He said the age threshold associated with the beginning of a loss of uterine function was unlikely to be absolute.

Professor Kovacic added: “It provides important information for patients and offers a valuable foundation for future research aimed at identifying novel biomarkers of uterine ageing.”

Dr Ippokratis Sarris, chair-elect of the British Fertility Society, called for more research.

He said pregnancies could carry greater risks for older women and recommended thorough health checks and counselling for couples beginning fertility treatment.