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A woman has given birth to the first baby to be conceived after an undeveloped human egg had been "ripened" in the laboratory and frozen before being fertilised using IVF.
The procedure - a world first - marks an important development in the ability to offer young women with cancer the capacity to retain their fertility after a bout of sterilising chemotherapy.
The unnamed woman lived in Canada and her baby girl was doing well, said Hananel Holzer of McGill University's Reproductive Centre in Montreal. Three other women were pregnant following the same procedure.
Until recently it has proven difficult to stimulate the development of immature human eggs in the test tube and freeze them until such a time when the woman requests to get pregnant with IVF treatment.
But Dr Holzer and his team has managed to do both and in the process opened the way for many women with cancer or diseases such as polycystic ovarian syndrome to become pregnant later in life when they are ready or healthy enough to start a family.
Dr Holzer took immature human eggs from 20 women with polycystic ovarian syndrome and matured them in the test tube by bathing them in a cocktail of nutrients.
The laboratory development of the immature eggs meant that the women did not need to undergo hormonal stimulation, which artificially matures eggs in the ovary but carries its own health risk, especially for women with polycystic ovarian syndrome.
"Unfortunately, some patients seeking fertility preservation may not have enough time to undergo ovarian stimulation, or may suffer from a medical condition deemed by some oncologists as a relative contra-indication to hormonal stimulation, such as oestrogen-receptor-positive breast cancer," Dr Holzer said.
Under such circumstances, eggs could be collected from a woman's ovaries without hormonal stimulation and then matured in the laboratory before being frozen until she was ready to carry a baby following IVF treatment, he said.
"We have demonstrated for the first time that it is possible to do this and, so far, we have achieved four successful pregnancies, one of which has resulted in a live birth," he said.
"These results are preliminary and the pregnancy rate is probably associated with a learning curve. Indeed, three of the pregnancies were achieved in the last five patients," he told the European Society for Human Reproduction and Embryology in Lyon.
Treating cancer patients with the technique had not yet been attempted but it potentially offered a safer route to motherhood than transplanting ovarian tissue back into the woman, which ran the risk of re-introducing cancerous cells, he said.
Other experts welcomed the findings but warned that further research is needed before it can be considered a safe option for women with cancer or polycystic ovary disease.
"Each step in this work has been achieved before, but this is the first time they have been successfully strung together," said Robin Lovell-Badge, head of developmental genetics at the MRC National Institute for Medical Research.
Test-tube pioneer Lord Robert Winston said: "This is an important step forwards that could potentially help women with fertility issues, including those undergoing cancer treatment."
- INDEPENDENT
