In a world first, a woman in her 20s has given birth to a healthy baby boy after doctors restored her fertility by transplanting ovarian tissue that had been removed while she was still a child.

According to doctors, there have previously been reports of women going on to have babies after ovarian transplantation, however in these cases, the tissue had first been removed when the women were adults.

This marks the first time a pregnancy has been successful following the removal of ovarian tissue from a child and until now, it was not even clear whether immature ovarian tissue could produce mature eggs.

The woman was born in the Republic of Congo and emigrated to Belgium when she was 11. At the age of five, she was diagnosed with sickle-cell anaemia, a serious disorder of the blood, which can result in severe pain, tissue damage and organ damage.

In Belgium, doctors felt that her condition was so severe, she would need a bone marrow transplant. As part of this procedure, the immune system needs to be disabled to prevent rejection of the bone marrow. This is usually done with chemotherapy or radiotherapy, which can permanently destroy the functioning of the ovaries.

In the case of this patient, doctors removed her right ovary when she was 13 years and 11 months old, and froze fragments of the tissue. At this point, while her breasts had started to develop, she had not had her first period.

She was then treated with chemotherapy.

The bone marrow transplant was successful, however her remaining ovary failed when she was 15, so doctors gave her hormone replace therapy (HRT) to induce the onset of menstruation.

Ten years after this, the patient said that she would like to become pregnant and underwent counselling. Doctors then stopped her HRT and thawed some of the frozen ovarian tissue. Four of these fragments were grafted onto her remaining ovary, while 11 other fragments were grafted onto other sites in her body.

This transplanted tissue started responding and growing follicles that contain maturing eggs. The patient began menstruating five months after this.

Over two years after the ovarian tissue transplantation, at the age of 27, she became pregnant naturally with her partner. In November 2014, she gave birth to a healthy boy weighing six pounds and nine ounces.

"This is an important breakthrough in the field because children are the patients who are most likely to benefit from the procedure in the future. When they are diagnosed with diseases that require treatment that can destroy ovarian function, freezing ovarian tissue is the only available option for preserving their fertility," explained the lead doctor on this case, Dr Isabelle Demeestere, of the Fertility Clinic and Research Laboratory on Human Reproduction at Erasme Hospital, Université Libre de Bruxelles.

However, she pointed out that more investigation is needed in very young girls, as this particular patient ‘had already started puberty even although she had not started menstruating'.

"In addition, the procedure also raises some controversial issues. For instance, because it is an invasive procedure and because the lifespan of the graft is limited, should it be used to induce puberty and menstruation, rather than to restore fertility, when HRT is an efficient, standard, and non-invasive alternative for inducing puberty?

"Should the procedure only be proposed for patients with a high risk of ovarian failure or for those at low risk as well? We think, at present, that cryopreserved ovarian tissue should be used only for fertility restoration in patients at high risk of ovarian failure, and not for puberty induction or for restoring menstrual cycles in adults," Dr Demeestere said.

She noted that this patient's ovary continues to work normally and there is no reason why she cannot go on to have more babies.

"She also has the possibility of undergoing a second transplantation with the remaining frozen tissue if the graft stops working, as we didn't transplant all the ovarian tissue the first time. We have another patient who became pregnant after ovarian transplantation, and she had two babies born after two graft procedures," Dr Demeestere added.

Details of this case are published in the journal, Human Reproduction.

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