A new type of ‘three-person IVF’ has allowed a previously infertile couple to have a baby in a world first.

The baby boy was born in Ukraine using a technique known as pronuclear transfer, a method experts have called “highly experimental”.

Doctors in Kiev fertilised the mother’s egg with the father’s sperm, and then placed the combined cells into an egg donated by a third woman.

The egg was then implanted into the womb of the 34-year-old mother, who gave birth naturally, Valery Zukin, who led the procedure, told The Independent.

The couple, who had been trying to conceive for over ten years, “could not believe it, especially in the first weeks of pregnancy”, he said.

‘Three-person IVF’ has previously been used to prevent babies from inheriting serious genetic disorders, but this is the first time it has been used to treat infertility.

The director of Kiev’s Nadiya clinic told The Times the technique could in future be used to help woman in their 40s give birth using their own eggs.

However, scientists have warned the treatment has not been scientifically tested and as such could be unsafe or give women false hope.

Dr Zukin said the treatment could help women who experience a condition known as embryo arrest, which affects around one in 150 IVF patients and causes embryos to stop growing before they can be implanted.

He shared a video on his Facebook page yesterday of an IVF fertilisation in progress, with congratulatory messages posted underneath by his contacts.

"Pronuclear transfer is highly experimental and has not been properly evaluated or scientifically proven,” said Professor Adam Balen, chairman of the British Fertility Society, reported the BBC.

"We would be extremely cautious about adopting this approach to improve IVF outcomes."

The baby has inherited its genetic identity from its parents, with a tiny amount of DNA from the second woman. He was born on 5 January, the clinic announced yesterday.

In response to experts questioning the treatment's safety, Dr Zukin said: "They are partly right. But how we could confirm the safety if we will not do this?"

The couple had been trying to conceive for more than a decade with no success, despite having undergone four failed cycles of IVF.

The Human Fertilisation and Embryology Authority (HFEA) approved the use of ‘three-person IVF’ to prevent genetic diseases in the UK last month in a historic decision giving the controversial new fertility method the final go-ahead.

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One in 200 children are born with faulty genes in their mitochondria, small structures inside cells that generate energy.

This can lead to a wide range of potentially fatal conditions affecting vital organs, muscles, vision, growth and mental ability.

The world’s first baby was born using the ‘three-person IVF’ in Mexico last year.

The baby's mother, from Jordan, had Leigh syndrome – a potentially fatal disorder that affects the developing nervous system and would have been passed on in her mitochondrial DNA.

Dr John Zhang, of the New Hope Fertility Centre in New York, and his team took the nucleus from one of the mother’s eggs, containing her DNA, and implanted it into a donor egg that had its nucleus removed but retained the donor’s healthy mitochondrial DNA.

Dr Zhang told the New Scientist that, as the technique has not yet been approved in the US, the team went to Mexico where “there are no rules”.

Commenting on the use of the method to treat infertility, Sarah Norcross, director of the Progress Educational Trust, called it "unorthodox" and said scepticism was necessary when assessing future implications.

'If this child appears healthy then that is good news, but we should be sceptical about the merits of mitochondrial donation when it is used as an unorthodox fertility treatment technique," she said.

"The UK has seen some very thorough reports on the safety and efficacy of mitochondrial donation, but these assessed risk only in relation to patients wishing to avoid transmitting mitochondrial disease to their children.