What are 'three-parent babies' and how does the IVF treatment work?

Metro

17-07-2025

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Eight healthy babies have been born in the UK using a groundbreaking three-person IVF technique.
The four boys and four girls, including a set of identical twins, are all doing well after delivery, with one other woman currently pregnant.
This new scientific method, pioneered by a team in Newcastle, is designed to prevent children from being born with mitochondrial diseases which could have been passed down to them from their mothers.
Most importantly, thanks to the IVF technique, none of the eight babies show signs of having mitochondrial DNA disease, which usually affects around one in 5,000 births.
Professor Sir Doug Turnbull is part of the Newcastle University research team which came up with the method.
He explained: 'Mitochondrial disease can have a devastating impact on families.
'Today's news offers fresh hope to many more women at risk of passing on this condition who now have the chance to have children growing up without this terrible disease.'
The babies will all be tested at 18-months-old and again aged five to ensure they are still developing normally and have no signs of mitochondrial disease.
Professor Bobby McFarland, director of the NHS Highly Specialised Service for Rare Mitochondrial Disorders at Newcastle Hospitals NHS Foundation Trust, said he was confident the babies will continue to develop normally.
He added: 'If we're not picking up subtle signs of problems at five, then we're really very clear that is not going to be a problem.
'In my work…I see children in intensive care units up and down this country and that's not pleasant.
'It's very difficult for families to deal with these diseases, they are devastating, so to see babies born at the end of this is just amazing really.'
This three-person IVF technique, called pronuclear transfer (PNT), involves taking the egg from an affected mother, sperm from her partner and an egg from a donor who is free from disease.
After the egg is fertilised, scientists transplanted the nuclear genome from the egg carrying the mitochondrial DNA mutation into an egg donated by an unaffected woman that had had its nuclear genome removed.
The nuclear genome from the mum contains all the genes essential for a person's characteristics, such as hair colour and height.
The procedure means the baby will inherit its parents' nuclear DNA, but the mitochondrial DNA is mainly inherited from the donated egg.
IVF is a fertility treatment designed to help people get pregnant and have children.
A woman's eggs are fertilised with sperm in a laboratory, and the embryo is then placed into the womb.
A full cycle of IVF takes between three to six weeks to complete, usually following six steps, and involves eggs being collected and fertilised before the embryo is implanted back into the womb.
Thanks to scientific progress in this area, parliament changed the law in 2015 to allow mitochondrial donation treatment.
By 2017, the Newcastle Fertility Centre became the first and only national centre allowed to perform PNT.
Approval is given on a case-by-case basis by the UK's Human Fertilisation and Embryology Authority (HFEA).
The chance of success with IVF can depend on many factors, such as: What is causing your fertility problems
Your age
Your body mass index
Whether you smoke or drink alcohol
If you are aged 39 or under, you could be eligible for three full IVF cycles, and if aged between 40 and 42 you could receive one full cycle paid for by the NHS.
The eligibility criteria could be different depending on where you live in the UK, as different integrated care boards use different guidelines to make these decisions.
If not eligible under the NHS, there are private clinics which can offer paid-for IVF treatment.
Peter Thompson, chief executive of the HFEA, said: 'Ten years ago, the UK was the first country in the world to licence mitochondrial donation treatment to avoid passing the condition to children.
'For the first time, families with severe inherited mitochondrial illness have the possibility of a healthy child.
'Although it's still early days, it is wonderful news that mitochondrial donation treatment has led to eight babies being born.
'Only people who are at a very high risk of passing a serious mitochondrial disease onto their children are eligible for this treatment in the UK, and every application for mitochondrial donation treatment is individually assessed in accordance with the law.'
Mitochondrial disease is a complex illness where the mitochondria in the body's cells do not produce enough energy.
The mitochondria is like the power station of our cells, providing the energy needed for our tissues and organs to work properly. More Trending
Each person with the disease is affected differently because there is a huge variety in how many cells are affected and where they are in the body.
Some specific illnesses, such as Alper's disease, Leigh's disease, MELAS and MERRF, occur when the same areas of the body are affected in the same way by the disease.
There is no cure for mitochondrial disease, and treatment is designed to relieve symptoms.
If sufferers develop another disease, increasing stress on their body's metabolism, their mitochondrial disease could get worse due to the extra stress put on cells.
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