A woman has given birth in London after doctors restored her fertility using frozen ovarian tissue removed when she was a young child.
The 24-year-old is thought to be the first in the world to have a baby after having an ovary frozen before the onset of puberty.
Moaza Al Matrooshi, whose son was delivered at the privately-run Portland Hospital yesterday, told the BBC: "It's like a miracle.
"We've been waiting so long for this result - a healthy baby."
Her doctor, Sara Matthews, a consultant in gynaecology and fertility, said she was overjoyed for the family - and delighted by the hope it offered to others too.
"This is a huge step forward. We know that ovarian tissue transplantation works for older women, but we've never known if we could take tissue from a child, freeze it and make it work again."
Doctors say it will give hope to many other girls and young women who risk losing the chance of motherhood as a result of treatment for cancer, blood or immune disorders.
Frozen for the future
Moaza Al Matrooshi, who is from Dubai, was born with beta thalassaemia, an inherited blood disorder that is fatal if untreated.
She needed chemotherapy, which damages the ovaries, before receiving a bone marrow transplant from her brother at Great Ormond Street Hospital in London.
So, prior to treatment, when she was nine years old, she had her right ovary removed in an operation in Leeds, where the tissue was frozen.
Fragments of her ovarian tissue were mixed with cryo-protective agents and slowly reduced in temperature to minus 196C, before being stored under liquid nitrogen.
Last year, surgeons in Denmark transplanted five slivers of the ovarian tissue back into her body - four were stitched on to her failed left ovary and one on to the side of her uterus.
Moaza had been going through the menopause. But after the transplant, her hormone levels began returning to normal, she began ovulating and her fertility was restored.
In order to maximise the chances of having a child, Moaza and her husband Ahmed underwent IVF treatment.
From the eight eggs that were collected, three embryos were produced, two of which were implanted earlier this year.
Moaza said: "I always believed that I would be a mum and that I would have a baby.
"I didn't stop hoping and now I have this baby - it is a perfect feeling."
She also thanked her mother, whose idea it was to save her young daughter's ovarian tissue so that she might be able to have a family in the future.
Dr Sara Matthews, who conducted the fertility treatment, said: "Within three months of re-implanting her ovarian tissue, Moaza went from being menopausal to having regular periods again.
"She basically became a normal woman in her twenties with normal ovary function."
Prof Helen Picton, who leads the division of reproduction and early development at the University of Leeds, carried out the ovary freezing.
She told me: "This is incredibly encouraging. Moaza is a pioneer and was one of the first patients we helped back in 2001, before any baby had been born from ovary tissue preservation.
"Worldwide more than 60 babies have been born from women who had their fertility restored, but Moaza is the first case from pre-pubertal freezing and the first from a patient who had treatment for beta thalassaemia."
Researchers in Leeds have been at the forefront of ovarian tissue freezing.
In 1999 scientists from Leeds were instrumental in performing the world's first transplant of frozen ovarian tissue.
Prof Picton said that in Europe alone, several thousand girls and young women now had frozen ovarian tissue in storage.
This is usually done prior to patients receiving chemotherapy or radiation treatment, both of which damage fertility.
Moaza still has one embryo in storage as well as two remaining pieces of ovarian tissue.
She said she definitely plans to have another baby in the future.
Earlier this year a cancer patient from Edinburgh became the first UK woman to give birth following a transplant of her frozen ovary tissue.
The mother, who conceived naturally, wished to remain anonymous.
Last year a woman in Belgium gave birth using ovarian tissue frozen when she was 13.
Unlike Moaza, she had begun going through puberty when her ovary was removed.
The first woman in the world to give birth following the transplantation of her own ovarian tissue was in Belgium in 2004.