What to Know About Your Blood Type 

Shandra Martinez

| 4 min read

Preparation for blood test by female doctor medical uniform in white bright room
Platelets, plasma, red blood cells and white blood cells: Everyone’s blood has these same four components. But that’s where all the similarity ends. Everyone’s blood also contains antigens – parts of the blood that are more personalized. That’s why knowing your specific blood type, and what this means for your health, is important for everyone. Let’s look at the most common blood types and what you should know about them.

Blood groups and blood types 

Our blood types don’t change over time. We are born with a specific type, depending on our parents’ blood types, just like other inherited genetic traits like hair and eye color. Here’s a quick explainer on the major blood groups, as compiled by The Red Cross, which has a huge volunteer blood donor base and is the biggest blood and blood component supplier in the United States.
There are four major blood groups: A, B, AB and O. Your blood group depends on A and B antigens, and if these antigens are found on your red blood cells. Once this is known, your more specific blood type depends on whether your blood has an Rh factor protein. If it does, your blood type is a positive (+). If it does not, it’s a negative (-). Here are a couple examples:
Blood type A+: This is someone who has A antigens in their blood, and also the presence of an Rh factor protein.
Blood type B-: This person has B antigens in their blood, but no Rh factor protein.
Blood type AB+: This is someone who has both A and B antigens present, as well as the Rh factor protein.
Blood type O+: This person’s blood has neither A or B antigens, so it is classified as blood group O. It does have an Rh factor protein, so it makes the type an O+.

Most common blood types

Using this method of sorting the blood groups, the most common blood types are A+, A-, B+, B-, O+, O-, AB+ and AB-. But all these blood types are not evenly spread out over the population, just like there are not the same number of people who have green eyes compared to blue.
The most common blood type in the U.S. is Group O. People with O+ or O- blood make up about 45% of the population. That number is higher among Hispanics and Blacks, according to The Red Cross.

Universal donors

If someone has O- blood, they are in high demand as a blood donor. This is because their blood type is known as a universal donor. Blood type O- can be used in blood transfusions to a person with any blood type, according to the Red Cross. This means it’s typically in short supply in hospitals where it is needed for emergency blood transfusions or for specialized procedures, like those for young children who are immune-deficient.
What your blood type says about your health. There has been research that has shown your blood type can give insight into potential health issues. Some recent findings include:
  • People with A and B blood types have an increased risk of blood clots compared to those with type O blood. They are 50% more likely to develop deep vein thrombosis – blood clots in the legs – than people with type O blood, according to a study published in an American Heart Association journal.
  • People with A and B blood types also have a 47% higher risk for pulmonary embolisms, which is when a blood clot travels to the lungs, as compared to those with type O.
  • People with A and B blood types are 8% more likely to have a heart attack than those with type O blood.
  • People with A and B blood types are 10% more likely to have heart failure than those with type O.
Photo credit: Getty Images

A Healthier Michigan is sponsored by Blue Cross Blue Shield of Michigan, a nonprofit, independent licensee of the Blue Cross Blue Shield Association.
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