Blood that is type O positive has two main characteristics: an absence of blood antigens A or B and a positive Rhesus (Rh) factor. According to the American Red Cross, O positive is the most common blood type, shared by 38 percent of the U.S. population.
There are eight common blood types an individual inherits based on his or her parents’ combined blood types: • A positive • A negative • B positive • B negative • AB positive • AB negative • O positive • O negative
Because mismatched blood antigens can target a blood recipient’s immune system, only certain blood-type combinations are compatible.
Blood Typing for Transfusions
In the event a person with O positive blood should need a transfusion—due to trauma, surgery, cancer, blood disorders or other illnesses—he or she can receive only O positive or O negative blood. As a result, O positive blood is in high demand, trailing only O negative blood, which is used in emergencies when there isn’t time to type a recipient’s blood. Those who are O positive can donate blood to any of the other positive blood types. According to the Red Cross, this means: • 84 percent of the population can receive their red blood cells • 100 percent of the population can receive their platelets • 45 percent of the population can receive their plasma
Double Red Cell Donation
Because of the high demand, individuals with O positive blood are encouraged to donate double red cells. This is an automated process in which a machine extracts twice the number of red blood cells found in one unit of whole blood and returns the other blood components (platelets and plasma) to the donor. According to the Red Cross, the collected red blood cells are most likely to benefit trauma and surgery patients. Individuals are eligible to donate double red cells once every 112 days, or three times per year.
Rh Incompatibility and Pregnancy
As mentioned previously, the positive or negative quality of a blood type refers to its Rh factor. In addition to typing for blood transfusions, Rh incompatibility is a potential concern during pregnancy. About 85 percent of people are Rh positive, according to an article published on Kidshealth.org. If a woman who is Rh negative and a man who is Rh positive (including O positive) conceive a baby, there’s a 50 percent chance that the baby will have Rh-positive blood, causing the mother’s body to produce antibodies to attack the foreign substance. Although the resultant Rh disease once posed significant risks to mother and newborn, doctors today prevent problems by administering two Rh immune-globulin shots during an at-risk woman’s first pregnancy, the article states.
O Positive Personality
The Japanese believe that blood type influences one’s personality. People with type O blood (regardless of Rh factor) are considered to be outgoing and self-confident, according to an article in Science World magazine. Many famous Japanese baseball players have type O blood, the article adds.