The first woman to have an ovary frozen before the onset of puberty has given birth to a baby boy. As a nine-year-old child, Moaza Al Matrooshi, now 24, suffered from a severe blood disorder, beta-thalassemia, and needed chemotherapy in preparation for a bone marrow transplant to treat the condition. The chemotherapy was likely to leave her infertile, so she chose to have her right ovary removed and the tissue from it frozen before she underwent treatment.

“It is the first time that the success of the procedure has been shown in a pre-pubertal girl, and I’m delighted that this young woman has had her baby,” says professor Helen Picton, head of the Division of Reproduction and Early Development at the University of Leeds, the facility where Matrooshi had her tissue frozen.

Doctors left the other ovary in her body, but the toxic impact of the chemotherapy drugs on the remaining ovary resulted in menopause in Matrooshi’s early twenties. In 2015, doctors in Denmark, in consultation with experts at The Portland Hospital in the UK, transplanted pieces of her stored tissue into both her infertile ovary and the side of her womb. Experts at Portland then monitored her condition and soon noticed that Matrooshi’s menopause was reversing. “We knew that this process worked when tissue was replanted in older women but this wonderful event gives hope to many young girls who might be faced with cancer, blood or immune disorders where the treatment would make them infertile,” says Sara Matthews, a gynecologist at Portland who worked with Matrooshi.

The first woman in the world to give birth following the transplantation of her own ovarian tissue was in 2004. Researchers at the University of Leeds have been at the forefront of ovarian tissue freezing. In 1999, for example, scientists there were instrumental in performing the world’s first transplant of frozen ovarian tissue. Professor Picton is currently working on a technique to enable frozen immature eggs to be grown and fertilized in a lab before doctors transplant an embryo into the mother.

“We hope the new technologies that are coming on the block will enable us to grow the early stage eggs that we’ve preserved in the frozen tissue to full size and maturity in the laboratory and to fertilize them in vitro, with a view to transplanting the embryo back into the womb,” she says. “That sort of technology is suitable for those patients for whom transplantation of ovarian tissue is not an option…young cancer patients, for example, who might be at high risk of reintroducing cancer cells to the body through the transplantation of cryopreserved ovarian tissue.”

Her team will also use the technology for the in vitro growth and culture of ovarian tissue as a means of testing the ovarian toxicity of contemporary cancer drugs, a process Picton says will help doctors predict the likely risk to young patients of losing their fertility in the future.