Scientists have proved that it is possible for a mother's cancer cells to be passed to her unborn child.
There are very rare cases where a mother and child appear to share the same cancer, but in theory the child's immune system should block the cancer.
However, an analysis by a British-led team of one such case shows the cells which caused leukaemia in the child could only have come from the mother.
The study appears in Proceedings of the National Academy of Sciences.READ MORE
