Scientists say they have ‘rejuvenated’ human eggs in advance that could boost IVF success
New research suggests a protein injection could improve egg quality and IVF success for older women
Scientists say they have found a way to ‘rejuvenate’ human eggs in advance, an advance that could significantly improve IVF success rates for older women.
The research, revealed in an exclusive report by The Guardian, suggests that age-related defects in eggs, a major cause of IVF failure and miscarriage, could be reduced by supplementing eggs with a key protein. Experts believe the approach could help more women conceive with fewer IVF cycles.
The findings are being presented at the British Fertility Conference in Edinburgh and have been published as a preprint paper, meaning they are yet to undergo full peer review.
Why egg quality matters so much in IVF
Egg quality is the main reason IVF success rates fall sharply with age. As women get older, their eggs are more likely to contain abnormal numbers of chromosomes, which can prevent embryos from developing or lead to miscarriage.
According to the most recent UK figures, the average birth rate per embryo transferred is around 35% for women under 35. For women aged 43 to 44, that figure drops to just 5%. The average age of women starting fertility treatment in the UK for the first time is now over 35.
This age-related decline is also why the risk of chromosome conditions such as Down’s syndrome increases with maternal age.
How scientists ‘rejuvenated’ human eggs
The new approach focuses on a crucial stage of egg development called meiosis. This is when eggs divide and prepare their genetic material so it can combine with sperm.
In younger eggs, pairs of chromosomes stay tightly aligned so they divide evenly. In older eggs, those pairs can loosen and move unpredictably, leading to embryos with too many or too few chromosomes.
Researchers previously discovered that levels of a protein called Shugoshin 1, which helps hold chromosome pairs together, decline as eggs age.
In the latest experiments, scientists injected this protein directly into donated human eggs. The results were striking.
Using eggs donated by patients at the Bourn Hall fertility clinic in Cambridge, the team found that 53% of untreated eggs showed chromosome defects. In treated eggs, this fell to 29%.
Among eggs from women over 35, the proportion with defects dropped from 65% to 44%, although researchers stressed this result was not statistically significant due to the small number of eggs tested.
‘A very prominent improvement’
Prof Melina Schuh, director at the Max Planck Institute for Multidisciplinary Sciences in Göttingen and a co-founder of Ovo Labs, said the results suggest a meaningful improvement in egg quality.
“Overall we can nearly halve the number of eggs with [abnormal] chromosomes. That’s a very prominent improvement,” she said.
She added: “Most women in their early 40s do have eggs, but nearly all of the eggs have incorrect chromosome numbers. This was the motivation for wanting to address this problem.”
Prof Schuh described the findings as restoring eggs to a more youthful state rather than changing them in a new way.
“What is really beautiful is that we identified a single protein that, with age, goes down, returned it to young levels and it has a big effect,” she said. “We are just restoring the younger situation again with this approach.”
What this could mean for IVF patients
Dr Agata Zielinska, co-founder and co-CEO of Ovo Labs, said the technique could reduce the emotional and physical toll of repeated IVF cycles.
“Currently, when it comes to female factor infertility, the only solution that’s available to most patients is trying IVF multiple times so that, cumulatively, your likelihood of success increases,” she said.
“What we envision is that many more women would be able to conceive within a single IVF cycle.”
If confirmed in larger clinical trials, the approach could mark a major shift in fertility treatment for women in their late 30s and 40s.
What the treatment would not do
The scientists were clear that this technique would not extend fertility beyond menopause, when the egg reserve has already been depleted.
At present, the only routine microinjection used in IVF is intra-cytoplasmic sperm injection, or ICSI, where a single sperm is injected into an egg. There are currently no approved treatments involving injecting substances into eggs to improve quality.
The research team said they do not anticipate major safety concerns and are already in discussions with regulators about running a clinical trial. A key question will be whether the improvement in egg quality leads to embryos with fewer genetic errors and higher live birth rates.
Expert reaction: ‘Really promising’
Independent experts have described the findings as encouraging, while stressing that more research is needed.
Dr Güneş Taylor, from the University of Edinburgh, who was not involved in the study, said: “This is really promising.”
“This is really important work because we need approaches that work for older eggs because that’s the point at which most women appear,” she said. “If there’s a one-shot injection that substantially increases the number of eggs with properly organised chromosomes, that gives you a better starting point.”
For many women navigating IVF later in life, that better starting point could make a life-changing difference.
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Ruairidh is the Digital Lead on MadeForMums. He works with a team of fantastically talented content creators and subject-matter experts on MadeForMums.