A father’s age may impact the success of an IVF pregnancy and an older male biological clock can make miscarriages more likely, new research has found.
While men are able to produce sperm and conceive a child throughout their lives, their fertility has been known to decline with age. Previously, it was known that sperm from men over the age of 45 has a lower chance of successfully fertilising an egg during the IVF (in vitro fertilisation) process.
Now, a new international study has revealed that IVF cycles involving male partners over the age of 45 carry significantly increased miscarriage risks and lower live birth rates - even if the eggs come from a younger woman.
The study analysed 1,712 cases of IVF between 2019 and 2023 across centres in Italy and Spain, noticing that miscarriages were notably higher among couples where a male partner was over 45.
Participants were divided into two groups: men aged 45 or younger made up 1,066 of the group, while there were 646 in the category over 45. All cycles used fresh donor oocytes - the cell in an ovary which may form an egg - with a mean donor age of 26.1 years, while sperm was frozen from male partners. Female recipients had a mean age of 43.3 years.
For older prospective fathers, the miscarriage rate reached 23.8 per cent compared to 16.3 per cent in the younger paternal age group. Live birth rates were significantly lower in the older paternal age group at 35.1 per cent, compared to 41 per cent for men aged 45 or younger.
The results of the study challenge a common assumption that sperm age has little impact following fertilisation.
“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,” said embryologist Dr Maria Cristina Guglielmo, who is set to present the study at the 41st annual meeting of the European Society of Human Reproduction and Embryology (ESHRE).
“Even when using eggs from young, healthy donors and transferring only a single, high-quality embryo, we observed poorer outcomes in men over 45.”
She added there was growing evidence linking advanced paternal age to increased risk of neurodevelopment disorders in children, and that any future research would investigate the long-term health and developmental outcomes of children conceived through donor egg cycles with older fathers, where maternal factors are minimised so the paternal effects can be isolated more clearly.
“Together, these factors affect both the genetic integrity and the functional quality of sperm, which can impair embryo development and contribute to a higher risk of miscarriage,” Dr Guglielmo added.
She said the findings underscore a need for fertility clinics to recognise the role of paternal age, ensuring that male patients are fully informed about how their age can impact their fertility potential, pregnancy success and miscarriage risk.
Professor Dr Carlos Calhaz-Jorge, immediate past chair of ESHRE, said, “This is an important paper that draws attention to an often-overlooked factor in the IVF field. Although it might be interesting to further subdivide the ‘older paternal age’ group (for instance, would men over 55 show even poorer outcomes?), the results presented should be seriously considered during the counselling process for couples in which the male partner is over 45.”
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