Fertility doctors in France have announced the birth of the first baby to be born to a cancer patient from an immature egg that was matured in the laboratory, frozen, then thawed and fertilised five years later. A recent paper in the leading cancer journal -- Annals of Oncology - describes how the baby boy was born to a 34-year-old French woman, who was infertile because she had been treated with chemotherapy for breast cancer five years earlier. Before she started her cancer treatment, doctors removed seven immature eggs from her ovaries and used a technique called in vitro maturation (IVM) to enable the eggs to develop further in the laboratory. The mature eggs were then frozen by means of vitrification, which freezes the eggs very rapidly in liquid nitrogen to reduce the chances of ice crystals forming and damaging the cell. Until now, there have been no successful pregnancies in cancer patients after eggs that have undergone IVM and vitrification, although some children have been born as a result of IVM followed by immediate fertilisation and transfer to the patient without freezing.