Women having sex changes on the NHS are being given free fertility treatment so they can have babies after they become men.

At least three British men who were born female are ‘on the brink’ of becoming parents using IVF techniques, according to a top doctor.

And dozens more are now having their eggs frozen at NHS clinics before undergoing surgery or hormone therapy to switch sex.

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A medical first: Thomas Beatie, when pregnant for the first time. He was the first man to give birth and went on to have two more sons

The controversial treatment means that a British transgender man could soon become a parent – all funded by the taxpayer.

In rare circumstances, the man could become pregnant and give birth, although the vast majority of cases would involve implanting an embryo into a surrogate mother, often the man’s partner.

Last night critics said cash-strapped health authorities should not be spending up to £34,000 per patient to help them change sex and have children when they are rationing basic services such as cataract operations, hip replacements and even hearing aids.

Tory MP Peter Bone said: ‘I am not sure why the taxpayer should be funding this. I just sometimes ask if the NHS is getting its priorities right.’

But one of Britain’s leading sex change doctors defended the practice, saying patients undergoing gender reassignment surgery had as much right to preserve their fertility as young people with cancer who freeze their eggs or sperm before having chemotherapy.

Dr James Barrett, of the NHS Gender Identity Clinic in West London, said three of his patients who have transitioned from women to men were close to becoming parents.

He added that, in the last year, he had asked GPs to refer about 50 of his female-to-male patients to have eggs frozen, and about 100 of his male-to-female patients to have their sperm frozen.

‘As a matter of principle, anybody who loses their fertility as a result of standard NHS treatment should be able to preserve their fertility,’ he argued.

THE TRAILBLAZER: AMERICAN WHO BECAME WORLD'S FIRST PREGNANT MAN In 2008 Thomas Beatie proved it is possible for trans-men to physically have a baby themselves if they keep their female reproductive organs. He is pictured with his daughter Susan and son Jensen Most transgender parents who freeze their eggs before fully transitioning from female to male will attempt to have children through a surrogate. But in 2008 Thomas Beatie proved it is possible for trans-men to physically have a baby themselves if they keep their female reproductive organs. The former teen beauty queen from Honolulu had started taking testosterone at 23. In 2002 he underwent surgery to give him a more manly appearance. But he chose not to have a hysterectomy and at the age of 34 he conceived his daughter Susan with the help of an anonymous sperm donor. He went on to have two more sons. Advertisement

‘Why are people with cancer particularly magic and get this [NHS fertility treatment], and other people don’t? Transgender patients want to live like normal people. They want what everybody else gets as a matter of course.’

Some local NHS authorities had agreed to fund fertility treatment for his patients straight away, Dr Barrett said. Some refused while others took ‘months’ to decide.

According to NHS figures released under the Freedom of Information Act, the average cost of a female to male gender reassignment to the NHS is £29,975 and £13,867 for male to female.

Egg-freezing IVF could add around £2,500, plus £150 a year for storage for up to ten years.

IVF services are already stretched in the NHS, with some areas such as parts of Essex, denying such treatment to infertile couples.

THE CHAMPION: DOCTOR WHO HAS THREE MEN READY TO BE 'MOTHERS' Dr James Barrett, consultant psychiatrist and lead clinician at Charing Cross Gender Identity Clinic, believes that transgender men and women have just as much right as cancer patients to preserve their fertility through the NHS. Advertisement

One transgender candidate for the treatment is 17-year-old Riley Middlemore, born Rebecca, who wants to freeze eggs before transitioning to a man, so in the future – using donor sperm – his girlfriend would be able to become a surrogate and give birth to their child.

Last night, his mother Carrie said: ‘He’s very passionate about having his own children, but he wants his girlfriend to have the children – he doesn’t want to give birth.’

In 2008, American Thomas Beatie shocked the world by giving birth to a daughter, Susan, after changing gender.

Mr Beatie went on to bear two other children using donor sperm, because his wife had undergone a hysterectomy while he had kept his womb.

But Dr Barrett said that in most cases the child would be born with a surrogate and the role of the transgender man who provided the eggs ‘would be that of father’.

But Michael Nazir-Ali, the former Bishop of Rochester, said the procedure risked upsetting ‘the natural order’ and said children would be ‘confused by not knowing if the parent is a father or a mother’.

He added: ‘Any child is best brought up by knowing the biological father and biological mother.’

THE CANDIDATE: TEENAGER WHO WANTS TO FREEZE HIS EGGS Riley Middlemore hopes to freeze his eggs before making the full transition from female to male. The 17-year-old has revealed that he wants his girlfriend to act as a surrogate with his eggs so he can have his own biological children. Advertisement

But Dr Barrett said there was no evidence transgender people made worse parents than others, adding: ‘From adoption studies, they seem to be doing fine.’

No female to male transgender patient has yet completed this process in Britain, but Dr Barrett said: ‘There may be some who are on the brink of doing so,’ indicating there were three people in this position.

He told his transgender patients who were freezing their eggs that they had a ‘small, but not zero chance of their own DNA being in some baby in the future’ because fertility treatment was often unsuccessful. But he said egg freezing was about ‘preserving options’

Official figures show a success rate of just one baby for every 29 embryos created from frozen eggs.

About 15,000 people were referred to UK gender identity clinics last year, and since 2004, transgender people have been able to obtain a new birth certificate under their altered gender.

But whether a transgender man whose frozen eggs have been used to create a baby will be legally recognised as the child’s father, rather than their mother, remains to be seen.

Last year High Court judge Mr Justice Hickinbottom ruled that ‘JK’, who had switched from male to female, must be listed as ‘father’ on the birth certificates of her two children, conceived before she started hormone therapy.

JK had wanted to be listed simply as ‘parent’ citing her human right to keep her gender change private.