But despite this, and subsequent blood transfusions, the baby suffered a brain hemorrhage with devastating consequences.Some time later, as the medics tried to find out more about them, a sample of the mother’s blood arrived at a lab in Bristol run by researchers who study blood groups.They made a startling discovery: The woman’s blood was of an ultrarare type, which may have made her baby’s blood incompatible with her own.Through studying the mother’s blood sample, along with a number of others, scientists were able to unpick exactly what made her blood different, and in the process confirmed a new set of blood grouping—the “Er” system, the 44th to be described.These newer systems tend to involve blood types that are mind-bogglingly rare but, for those touched by them, just knowing that they have such blood could be lifesaving."