The baby was in danger. An emergency C-section was performed many weeks before the baby was due because the doctors at the UK hospital knew there was a problem with the fetus. Despite this, the baby suffered a brain hemorrhage and had to be hospitalized. It died.

There was no clear reason why the bleeding had happened. There was a hint in the mother's blood. A sample of the mother's blood was sent to a lab in Bristol run by researchers who study blood groups.

They discovered that the woman's blood type was ultra rare, which may have made her baby's blood incompatible with her own. It is possible that this caused her immune system to make antibodies against her baby's blood, which led to her child's death. Many decades ago, before doctors had a better understanding of blood groups, it was commonplace.

After studying the mother's blood sample, along with a number of others, scientists were able to unpick what made her blood different, and in the process confirmed a new set of blood grouping.

The main blood types are A, B, O, andAB. This isn't the only system. There are many ways of grouping red blood cells based on differences in the sugars on their skin. The grouping systems run at the same time, so your blood can be classified in different ways.

If someone receives incompatible blood from a donor, the recipient's immune system may react against them. It's important that donated blood is a good match for someone having a transfusion.

Each year researchers describe a new blood classification system. For people touched by these newer systems, knowing that they have rare blood types could save their life. The mystery of the latest blood system is the subject of this story.

It was back in 1982 that researchers first described an unusual blood type that was out there. At the time, the scientists could not go much further than that, but they knew they had a clue as to what the person's immune system was capable of.

In the years that followed, more people came up with these strange antibodies, but only a few times. These people came about thanks to blood tests. Nicole Thornton and her colleagues at the UK's National Health Service decided to look into what might be behind the antibodies. She said they work on rare cases. The problem begins with a patient.