Very common - 35.7% of US donors
A-positive is the second most common blood type in the United States, found in approximately 35.7% of US donors. People with A+ blood carry the A antigen on their red cells, produce anti-B antibodies, and carry the Rh-D antigen. A-positive blood is compatible with A-positive and AB-positive recipients for red cell transfusion.
Antigens present
A antigen, Rh-D antigen
Antibodies produced
Anti-B
Antigens are proteins on the surface of red blood cells. Antibodies are produced by the immune system against antigens it does not carry. When incompatible blood is transfused, antibodies bind to foreign antigens and trigger a haemolytic reaction.
Select your blood type:
Can donate red cells to:
2 compatible types
Can receive red cells from:
4 compatible types
| Population | Frequency |
|---|---|
| US blood donors (Red Cross estimate) | 35.7% |
| Global population (estimate) | 27.5% |
A-positive accounts for approximately 35.7% of US donors and about 27.5% of the global population. It is the second most common type after O-positive in the United States. Globally, distribution varies significantly by region - A blood group is more prevalent in Europe and North America than in sub-Saharan Africa or East Asia.
Research published in multiple large cohort studies suggests that people with blood group A may have a modestly higher risk of venous thromboembolism and possibly pancreatic cancer compared to O-type individuals. These are population-level associations from epidemiological studies and should not cause alarm - they do not change routine clinical management. Being A-positive does not mean you will develop any particular condition. Regular blood donation is safe for A-positive individuals (whole blood every 56 days, platelets every 7 days up to 24 times per year).
Note: Associations between blood type and disease risk are from observational studies and are not deterministic. They do not change your clinical management. Cite any specific associations with your clinician.
A-positive mothers are Rh-positive, so Rh incompatibility is not a pregnancy concern. There is a separate phenomenon called ABO incompatibility between mother and fetus - for example, an O-type mother carrying an A-type fetus. However, ABO incompatibility is usually mild because fetal ABO antigens are weakly expressed, and it rarely requires treatment beyond monitoring for newborn jaundice. If you are A-positive and pregnant, Rh-related anti-D prophylaxis is not needed.
Full Rh factor pregnancy guide +A-positive organ donors can give to A+ and AB+ recipients (following the standard ABO compatibility rules). As an A-positive recipient, you can receive organs from A+, A-, O+, or O- donors. This is a reasonably broad compatible donor pool. AB+ remains the most flexible recipient type overall. As with all transplants, HLA matching and crossmatch testing are required in addition to ABO compatibility.
ABO compatibility for organ transplant follows the same rules as transfusion - A+ can donate organs to: A+, AB+. However, HLA tissue matching and crossmatch testing are also required, and sensitisation from prior transfusions or pregnancies can restrict compatibility further.
Full organ transplant guide +A-type plasma contains anti-B antibodies. This means A plasma (both A+ and A-) can be given to A and O recipients (who do not carry the B antigen). For plasma donation, AB-type is the most versatile universal plasma donor. If you are A-positive, platelet donation is a particularly high-value contribution - A-positive platelets are in demand and can be given to A+ patients without needing to consider ABO compatibility as strictly as for red cells.
Note: Plasma compatibility rules are the inverse of red-cell rules because plasma carries antibodies, not antigens. AB plasma is the universal plasma donor.
Plasma compatibility chart +