Sperm from men over the age of 45 are linked to higher IVF miscarriages and lower birth rates - even when young donor eggs were used

IVF involving men over the age of 45 is linked to increased miscarriage risks, a study has revealed.

Researchers found that a man’s age plays a significant role in their reproductive success, challenging the notion that sperm age has little impact once fertilisation has occurred.

They discovered that sperm from older men also led to lower live birth rates – even when young donor eggs were used.

And experts said their results should be considered during the IVF counselling process between doctors and patients.

The study, published in the journal Human Reproduction, analysed 1,712 egg donation cycles between 2019 and 2023 across six IVF centres in Italy and Spain.

All cycles used fresh donor eggs with an average donor age of 26 and frozen sperm from male partners. The fertilised eggs were then transferred to the intended mothers, who had an average age of 43.

Participants were divided into two groups – men aged 45 or younger and those over 45, and while fertilisation rates and embryo development were similar between the groups, differences emerged in the outcomes of the pregnancies.

Miscarriage rates – where the baby is lost before 24 weeks – were notably higher among couples where the male partner was over 45, reaching 23.8 per cent compared with 16.3 per cent in the younger paternal age group.

Live birth rates were also lower in the older paternal age group, at 35.1 per cent versus 41 per cent for men aged 45 or younger.

Discussing the findings, Dr Maria Cristina Guglielmo, an embryologist at the fertility clinic Eugin Italy, said: ‘Traditionally, maternal age has been the central focus in reproductive medicine, but our results show that the age of the male partner also plays a crucial and independent role.’

She explained that as men age, the continuous division of sperm stem cells increases the chance of DNA replication errors.

In turn, this can impair embryo development and contribute to a higher risk of miscarriage, she said.

Dr Guglielmo added: ‘Our findings underscore the need for fertility clinics to adopt a more balanced approach that recognises the role of paternal age.

‘Clinics should ensure male patients are informed about how advancing paternal age can impact fertility potential, pregnancy success and miscarriage risk.’