When the woman in question was 29, she underwent chemotherapy to treat breast cancer.
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However, her medical treatment meant she did not have enough time to be given ovarian stimulation hormones, which would have helped her produce mature eggs that could then be frozen.
As a result of the circumstances, scientists removed seven immature eggs from her ovaries.
They then used a method called in vitro maturation (IVM) to help mature the eggs in a lab.
After the eggs were matured, they were frozen using a process called vitrification.
Vitrification is a method that involves the rapid cooling of an egg or embryo, which reduces the possibility of ice crystals forming and damaging the cell.
When the woman was given the all-clear five years after being treated for breast cancer, she was informed she was infertile.
Of the seven eggs that had been removed, matured and frozen, five were fertilised sucessfully by scientists after being thawed.
After a single embryo was transferred to her womb, she became pregnant and gave birth to a son, named Jules, on 6 July 2019.
“We were delighted that the patient became pregnant without any difficulty and successfully delivered a healthy baby at term,” said Professor Michael Grynberg, head of the Department of Reproductive Medicine and Fertility Preservation at the Antoine Beclere University Hospital.
“My team and I trusted that IVM could work when ovarian stimulation was not feasible.”
Professor Grynberg said their work “represents a breakthrough in the field of fertility preservation”.
“IVM enables us to freeze eggs or embryos in urgent situations or when it would be hazardous for the patient to undergo ovarian stimulation. In addition, using them is not associated with a risk of cancer recurrence,” he stated.
The scientist explained that the team are “aware that eggs matured in the lab are of lower quality when compared to those obtained after ovarian stimulation”.
“However, our success with Jules shows that this technique should be considered a viable option for female fertility preservation, ideally combined with ovarian tissue cryopreservation as well,” he added.