Mitochondrial donation is a licensed IVF technique that replaces the faulty mitochondrial DNA in a woman’s egg with healthy mitochondrial DNA from a donor, reducing the risk of passing on serious inherited mitochondrial disease to a child. The UK became the first country in the world to regulate this treatment in 2015, and in 2025, a decade later, the results of the first babies born using the technique were finally published in a leading medical journal. Here is what mitochondrial donation actually involves, who can access it, and what the latest evidence shows.
What Is Mitochondrial Donation?
Mitochondria are found in almost every cell in the body and are responsible for producing the energy cells need to function. Unlike most of our DNA, mitochondrial DNA is passed down only from mother to child, so a woman carrying harmful mitochondrial mutations will pass them on to every child she has, though the proportion of affected mitochondria can vary between children.
The most established technique, known as pronuclear transfer, takes place after fertilisation. According to the Newcastle Hospitals NHS Foundation Trust, the nuclear genome, which carries the genes for individual characteristics such as hair colour and height, is transferred from the affected fertilised egg into a donor egg that has healthy mitochondria and has had its own nuclear genome removed. The resulting embryo inherits its parents’ nuclear DNA, but its mitochondrial DNA comes predominantly from the donor.
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Because the procedure happens after fertilisation rather than before, it is typically offered as part of an integrated programme alongside preimplantation genetic testing, or PGT, which screens embryos for the disease-causing mutation directly. In practice, pronuclear transfer tends to be offered to women who are unlikely to benefit from PGT alone, for example because almost all of their eggs carry very high levels of the harmful mutation.
Mitochondrial Disease: Why This Matters
Around 1 in 5,000 children is born with a mitochondrial DNA mutation that can cause serious disease. Because mitochondria supply energy to every cell, the organs and tissues with the highest energy demands, such as the heart, brain and muscles, tend to be affected most severely. Depending on the specific mutation and how much of it is present, children can experience a wide range of problems, including sight and hearing loss, diabetes, heart or kidney problems, and developmental or learning difficulties.
There is currently no cure for mitochondrial DNA disease. This is precisely why the treatment described above has focused on reducing transmission risk rather than curing the condition once a child is already affected, and why families with a known family history often seek genetic counselling long before deciding whether to try for a baby at all.
Who Can Access Mitochondrial Donation in the UK?
This treatment is only offered to women who are at very high risk of passing on a serious mitochondrial DNA disease, and every application must be individually approved. According to the Human Fertilisation and Embryology Authority, as of July 2025, 35 patients had been approved for treatment, with 25 having undergone pronuclear transfer. Only one clinic, the Newcastle Fertility Centre, is currently licensed to carry out the procedure, and referrals typically come through the NHS Highly Specialised Service for rare mitochondrial disorders rather than a standard fertility clinic pathway.
It is not a route to parenthood for people who are simply looking for donor eggs or sperm for other reasons, such as same-sex couples or single people building a family. Those situations are covered separately under standard IVF and egg donation rules, or under wider UK law governing human egg donation, both of which apply to a much wider group of intended parents than the narrow eligibility criteria used here.
What Do the Latest Results Show?
Findings published in 2025 in the New England Journal of Medicine confirmed that eight babies, four girls and four boys including one set of identical twins, had been born in the UK following pronuclear transfer, the technique used for mitochondrial donation. All eight were healthy at birth and were meeting their expected developmental milestones, with the disease-causing mitochondrial mutation either undetectable or present at levels well below the threshold usually needed to cause disease.
Three of the babies experienced minor early health issues, including a urinary tract infection and a temporary heart rhythm problem, though researchers do not believe these were directly caused by the procedure itself. Long-term monitoring of all children born through the programme is continuing, with follow-up planned until at least age five, so that researchers can build a fuller picture of how mitochondrial donation performs over time rather than relying solely on outcomes at birth.
Is Mitochondrial Donation Ethical?
Because a child born through this technique carries DNA from three people, it has remained ethically controversial since it was first debated in Parliament a decade ago. Critics have raised concerns about so-called designer babies and about children’s long-term wellbeing, while supporters argue that denying affected families any option at all would be equally difficult to justify on ethical grounds.
In practice, the contribution from the donor is limited to a very small amount of mitochondrial DNA, which affects cellular energy production rather than traits such as appearance, personality or intelligence. UK regulation reflects this distinction: the treatment is tightly restricted to cases of serious inherited disease risk, and it remains entirely separate from the wider legal framework covering egg donation for other fertility reasons, or from routine IVF in the UK more generally.
Mitochondrial Donation vs Standard Egg Donation
It is easy to confuse mitochondrial donation with standard egg or embryo donation, but the two serve very different purposes. Standard egg donation and egg freezing pathways exist to help people who cannot conceive using their own eggs, for reasons ranging from age to medical treatment, and the resulting child’s genetic material comes largely from the donor’s egg alongside the intended parent’s or donor’s sperm.
Mitochondrial donation, by contrast, still uses the intended mother’s own nuclear DNA, meaning the child remains genetically related to both parents in every meaningful sense; the donor’s contribution is limited to healthy mitochondria rather than a full genetic profile. Understanding this distinction also matters legally, since parental rights and responsibilities are treated differently depending on which type of donation is involved, as explained in our overview of donor parental rights in the UK.
A Timeline of Mitochondrial Donation in the UK
The path from legislation to the first published results took a decade, and understanding this timeline helps explain why the treatment remains so tightly restricted today.
| Year | Milestone |
|---|---|
| 2015 | UK becomes the first country in the world to pass legislation permitting the treatment under strict regulation |
| 2017 | Newcastle Fertility Centre becomes the first, and so far only, clinic licensed by the HFEA to perform the procedure |
| 2023 | Reports confirm that a small number of babies had already been born using the technique in the UK |
| 2025 | Peer-reviewed results published showing eight healthy babies born, with 35 patients approved in total |
Since the UK’s original legislation, Australia has also changed its law to permit a similar approach, and several other countries continue to debate whether to follow suit, watching the UK’s published results closely as part of that ongoing discussion.
Frequently Asked Questions About Mitochondrial Donation
How many babies have been born through this treatment?
As of the 2025 published results, eight babies had been born in the UK using pronuclear transfer, all reported healthy and meeting their developmental milestones, with a further pregnancy ongoing at the time of reporting.
Is mitochondrial donation the same as egg donation?
No. This treatment only replaces faulty mitochondrial DNA while keeping the intended mother’s own nuclear DNA, whereas standard egg donation uses a donor’s full genetic contribution alongside the intended parent’s or donor’s sperm.
Who is eligible for mitochondrial donation in the UK?
Only women at very high risk of passing on a serious mitochondrial DNA disease are eligible, and every case is individually assessed and approved by the HFEA before treatment can proceed.
Is it legal in the UK?
Yes. The UK became the first country to legalise mitochondrial donation in 2015, and it remains tightly regulated, with only one licensed clinic currently permitted to carry out the procedure.
Are there risks associated with the treatment?
Some carryover of the mother’s original mitochondrial DNA can occur, meaning the technique is currently considered a risk-reduction treatment rather than a guaranteed cure, and long-term monitoring of children is ongoing to better understand any longer-term patterns.
Mitochondrial donation remains one of the most tightly regulated fertility treatments available anywhere in the world, offering real hope to a small number of families affected by a serious inherited condition. If you are exploring other routes to parenthood, including egg or sperm donation and co-parenting, CoParents.co.uk connects you with a supportive UK community, and our guide to getting ready for a baby covers many of the practical questions worth asking before you start trying to conceive. Register for free to get started.