Knowing your blood type is an important piece of health information. Your blood group, also known as your blood type, determines compatibility if you need a blood transfusion. Blood types come in four main varieties: A, B, AB, and O. These letters refer to antigens, or proteins, on the surface of red blood cells.
Why is blood type important?
Blood type is important for a few key reasons:
- It determines who you can safely receive blood from or donate blood to.
- Certain blood types are associated with increased risk for some health conditions.
- Some studies suggest your blood type may even impact your personality and susceptibility to disease.
Knowing and sharing your blood type ensures you receive suitable blood if needed for a transfusion. It also allows others to safely donate blood to you.
How do you determine your blood type?
There are two main ways to determine your blood type:
- Blood typing test: This lab test, usually done with a blood sample from your arm, detects antigens on your red blood cells to reveal your blood group. This is the most accurate way to determine your type.
- DNA test: Services like 23andMe can determine your likely blood group through genetic analysis. However, confirmatory blood typing is recommended.
It’s possible to do an at-home blood type test as well, but professional testing is recommended for accuracy.
What are the 4 main blood types?
Human blood comes in four major types determined by the presence or absence of antigens A and B. Here are the four blood groups:
- Type A: Has only the A antigen on red cells.
- Type B: Has only the B antigen on red cells
- Type AB: Has both A and B antigens on red cells.
- Type O: Has neither A nor B antigen on red cells.
There is also a rare fifth type known as Bombay phenotype that lacks A, B, and H antigens. Additionally, each blood group has a positive or negative RhD protein on cells.
What is your blood type determined by?
Your blood type is inherited from your parents through two genes, one from each parent. The gene variants you inherit determine if you have A, B, both, or neither antigen on red blood cells. Here’s how it works:
- Gene variant IA produces antigen A.
- Gene variant IB produces antigen B.
- If you inherit IA from one parent and IB from the other, you’ll be type AB.
- If you inherit IA from both parents, you’ll be type A.
- If you inherit IB from both parents, you’ll be type B.
- If you inherit O from both parents, you’ll be type O.
The RhD protein is also inherited separately from another gene.
How common are different blood types?
The distribution of blood types varies globally but generally follows this pattern:
| Blood Type | Prevalence |
|---|---|
| O+ | 37% |
| A+ | 36% |
| B+ | 9% |
| AB+ | 4% |
| O- | 7% |
| A- | 6% |
| B- | 2% |
| AB- | 1% |
Type O positive and A positive are the most common, while AB negative is the rarest globally. Regional frequencies can vary.
Why share your blood type?
Telling people your blood type makes the most sense in these situations:
- Medical emergencies: If you’re unconscious, knowing your blood type helps ensure suitable transfusions.
- Hospital stays: Routine blood typing often occurs during hospitalization.
- Pregnancy: Blood type matters for mom/baby Rh compatibility.
- Donating blood: Blood banks need to know donors’ types.
- Genealogy research: Blood groups reflect ancestry and migrations.
- Dating: Some people consider blood type personality compatibility.
Outside of medical contexts, sharing blood type is optional based on your preferences.
How to find and share your blood type
Here are some ways to find and share your blood group:
- Get a blood test from your doctor, clinic, or blood bank.
- Check medical records from past blood typing tests.
- Use an at-home blood type kit, with confirmation testing.
- Add blood type to medical ID jewelry or records.
- Tell family members about your blood group.
- Enter blood type in health apps and profiles.
- Consider a blood type tattoo (not recommended).
Ideally, share verified blood types from tests rather than guesses or home kits alone.
Who can donate blood to whom?
Blood types must be compatible between donor and recipient for safe transfusions. Here are the compatible blood type pairings:
| Recipient Blood Type | Compatible Donor Blood Types |
|---|---|
| A+ | A+, O+ |
| A- | A-, O- |
| B+ | B+, O+ |
| B- | B-, O- |
| AB+ | A+, B+, AB+, O+ |
| AB- | A-, B-, AB-, O- |
| O+ | O+ |
| O- | O- |
Type O blood can donate to anyone due to lack of antigens. AB blood can receive from any donor due to having both A and B antigens. For safety, RhD negative people should only receive RhD negative blood.
Do blood types affect health?
Some research suggests associations between blood types and certain health risks or conditions. However, more study is needed to confirm links. Possible connections include:
- Type O: Lower risk of severe malaria but higher risk of severe blood loss from trauma.
- Type A: Higher risk of gastric cancer and blood clots. Lower heart disease risk in some studies.
- Type B: Higher risk of ovarian and cervical cancers. May be more susceptible to certain bacteria.
- Type AB: May have higher risk of cognitive impairment and memory loss in later life.
Talk to your doctor about how to manage any potential health risks related to your blood type.
Do blood types impact personality?
In some cultures, blood types are thought to influence personality and thinking style. However, no reputable scientific research has found a correlation between blood group and character traits. Any personality differences are likely due to upbringing, experiences, and genetics – not blood type.
Proposed blood type personality theories include:
- Type A: Sensitive, calm, creative.
- Type B: Passionate, flexible, individualistic.
- Type AB: Balanced, controlled, rational.
- Type O: Confident, self-determined, strong-willed.
While interesting, these suggested traits lack rigorous scientific evidence. Your blood type doesn’t define your personality.
Can your blood type change?
For most people, blood type remains constant throughout life. However, in very rare cases, blood type can change through:
- Bone marrow transplant: May convert recipient to donor’s blood type.
- ABO allele mismatch: If mother is O and fetus inherits O allele from father, infant may be born O then convert to AB later.
- Disease: Certain cancers, autoimmune disorders, or infections may damage red blood cell antigens and alter type.
Most of the time, though, your blood group remains your blood group for life.
Conclusion
Knowing your blood type has important medical implications for transfusion safety and donor compatibility. Sharing blood group with your doctor allows appropriate blood management if needed. Outside of health contexts, your blood type likely has minimal impact on your personality or life outcomes.