Scientists have been searching for ways to restore fertility
Cancer patient Ouarda Touirat, the first woman ever to become pregnant following an ovary transplant, has had a baby girl.
BBC News Online looks at the significance of the news.
What has happened?
Thirty-two-year-old Mrs Touirat had ovarian tissue removed prior from her left ovary to chemotherapy treatment for Hodgkin's lymphoma in 1997.
She stopped ovulating after her cancer treatment.
In April 2003, once she was declared cancer-free, her ovarian tissue was transplanted back into her body, immediately underneath her right ovary.
In June last year, tests showed she had begun to ovulate again.
This year, she conceived naturally. She has now given birth to a 3.72kg (just over 8lb) baby girl named Tamara.
The team treating the woman, from Belgium's UniversitÚ Catholique de Louvain say in the Lancet medical journal that all the evidence they have seen shows it was the transplanted ovarian tissue which ripened into the egg that was fertilised in the pregnancy.
They can say this because the egg follicle which ripened to produce that egg was seen growing on the tissue during the menstrual cycle during which Mrs Touirat became pregnant.
Why is this birth significant?
Women who undergo chemotherapy can lose their fertility because of the powerful drugs used in their treatment. Many will not. However, if radiotherapy treatment affects the ovaries, it immediately makes a woman infertile.
Scientists have been looking at how they can restore fertility to affected women.
Doctors began freezing cancer patients' ovarian tissue, prior to treatment, in the late 1990s.
Since then, teams in the US and Europe have worked first to successfully transplant the tissue back into women.
Both have shown normal ovarian function has been restored, and women have been having periods.
They were aiming to use embryos created using IVF to help women become pregnant.
But none of the women treated have become pregnant, making the Belgian case highly significant.
How do ovary transplants work?
Eggs are formed in cavities in the ovaries called follicles. As well as generating eggs, the ovaries pump out hormones that are vital for a woman to
Doctors take tiny strips of ovarian tissue, one to two millimetres thick, from the most productive part of the ovary.
These are then cut into sections and frozen in liquid nitrogen at a temperature of almost minus 200║C .
Ovarian tissue can be transplanted to any part of the body and still function.
Eggs are then removed and used in IVF treatment.
It is understood that in the Belgian case, the tissue was placed at the end of the fallopian tube under the right ovary, allowing a natural pregnancy.
What does this mean for other women?
It offers them great hope. For many women treated for cancer, the news they could be left infertile by their treatment is as devastating as the news of the cancer itself.
While experts in the field say they want to know more about the Belgian pregnancy, and to see pregnancies in other women, they say it is a major breakthrough.
Could it help other women?
Yes. Although researchers in the field are concentrating on helping cancer patients, the technique could also be used by women who want to extend their reproductive life.
The menopause puts an end to women's childbearing years. But this technique means they could have the option of having some of their ovarian tissue removed and frozen, and then stored.
Once they have been through the menopause, it could be replanted, offering them another chance of motherhood.
Is there anything which could stop more women benefiting?
Some fertility experts have expressed fears over a new EU directive which sets standards for the sterility and storage of human tissues and cells.
They fear these regulations would be very difficult for IVF clinics to meet.