Donating blood can be done every 12 weeks for males and every 16 weeks for females. The blood types are divided by two systems; the Rhesus and the ABO system, which are determined by the antigens and antibodies contained within the blood. Blood type O- is known as the universal donor as it does not contain any A, B or RhD antigens. However, people who are type O- can only receive O- blood in a transfusion as all other types contain either A, B or RhD antigens, or a combination of the three.
- ↑ NHS Choices, Blood Groups (2015). accessed 18/10/16 http://www.nhs.uk/Conditions/blood-groups/Pages/Introduction.aspx