To do this we consider:

We maintain a regular supply of all blood types to ensure the right blood is available to everyone who needs it. We need enough of the right types of blood to meet day-to-day patient needs and to cope with emergencies.

Which blood types are in demand?

Some blood types are in higher demand from hospitals than others.

For example, it's estimated that around 8% of people have O negative blood, but O negative makes up 13% of requests from hospitals.

This is because anyone can receive the red cells from O negative donors. So O negative red cells can be used in emergencies or when a person's blood type in unknown.

Sometimes we need to target specific blood types to increase stock levels. That's why we sometimes contact regular donors with the particular blood type we need, and ask them to give blood.