Surgeons are developing a pioneering procedure to use a uterus grown from human stem cells, giving fresh hope to women unable to bear children.

Professor Mats Brannstrom, who is a world expert on uterine transplantation after he and his Swedish team carried out nine such procedures, said that bio-engineering a uterus instead "may be the future".

He said the procedure was "10 to 15 years away", but explained how it could eliminate the need for the immuno-suppression required in current transplant recipients.

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The surgeon revealed that clinical trials in rats have already begun where lab-grown "uterus-patches" from stem cells were used.

Speaking at the Royal College of Obstetricians and Gynaecologists (RCOG) world congress, Prof Brannstrom also updated the audience on his ground-breaking transplant work - which is itself a new technique.

He said that "five healthy babies" had so far resulted from the complex transplantations his team carried out, in what is only their first human clinical trial.

The doctor then further delighted the 2,500 delegates in the Birmingham auditorium, revealing that one of the recipient women was now expecting her second child, from the same uterus.

Doctors in the UK were last year granted approval to carry out Britain's first 10 womb transplants.

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In a speech at the International Convention Centre (ICC), Prof Brannstrom said he had received ethical permission to use robotics to surgically harvest a uterus, in order to shorten the current 10-12 hour procedure by almost half.

Prof Brannstrom said: "There are things to optimise like non-surgical preparation.

"The robotic-assisted procedure - I think we can shorten the surgical procedure from 10-12 hours, to six to eight hours."

He also set out how the bio-engineering process could work.

Prof Brannstrom added: "Research on bio-engineered uterus, not in five years, but perhaps in 10-15 years.

"The concept is you create from stem cells of the recipient and transplant that into the recipient. You have a substitute for a damaged organ and keep it without immuno-suppression.

"We have started in a rat, and we have now published a paper where we have not been able to create a whole uterus but uterus-patches, bio-engineered. These may be the future, but we'll of course need a lot of research."

Prof Brannstrom, of the University of Gothenburg in Sweden, in an update on the transplant recipients said there was an 86% clinical progression rate and 71% "cumulative take-home-baby rate".

In all, nine women received transplants, but two were removed; one after infection developed and the other because of a thrombosis.

Of those, five women had successfully carried to term - although one had suffered two miscarriages and another had not yet become pregnant.

He said: "It's the first trial, so everything gets better.

"So at the moment the pregnancy rate or efficiency of the procedure is good."

The trial meant the Swedish recipients had to find their own donors, and in most cases these were close relatives.

In the first successful pregnancy, the donor was a family friend who was 61 years old at the time her uterus was harvested, and had been post-menopausal for seven years.

The recipient then became pregnant after the first round of IVF, and the baby boy was born in October 2014.

Prof Brannstrom told delegates the 16-month-old child, whose photograph drew a happy chorus of approval from the auditorium audience, was "healthy" and doing well.

The fifth pregnancy, from a sister-to-sister organ donation, came about after nine courses of IVF, resulting in a baby girl - the trial's first.

Before Prof Brannstrom's success using live donors, there had been two unsuccessful attempts at transplants, in Saudi Arabia in 2000 and then Turkey in 2011.

Clinical trials are now under way in other countries, aside from the UK - including Australia, India, and Singapore.

A meeting of world experts in the field is being held in Gothenburg on September 18, next year, with plans to create an international registry of all the patients.

Professor Alan Cameron, RCOG's vice president of clinical quality, said: "The RCOG congratulates the scientific advances made by Prof Mats Brannstrom and his team.

"Absolute uterine factor infertility (AUFI) affects around 12,000 women in the UK and it can have a devastating impact on people's lives - causing distress, depression, and the breakdown of relationships.

"Uterine transplantation is still a very new and experimental procedure which is currently only conducted through clinical trials.

"Prof Brannstrom has achieved exceptional results and we welcome further clinical trials in the hope that this becomes an established clinical treatment with high patient safety and efficiency."

Richard Smith, who leads the UK Uterine Transplant Research Programme, said: "Mats Brannstrom and his team have achieved a very important proof of concept and we heartily congratulate them once again.

"Most of all, we have great admiration for all organ donors and those ladies who volunteered to undergo this ground breaking surgery.

"Absolute uterine infertility is a huge and growing problem affecting tens of thousands of women in this country - and the success of the Swedish team shows that at least some of these women will be able to bear their own child where before there was no hope."