Humans have four main blood groups based on the presence or absence of specific antigens on the surface of red blood cells. These four blood groups are:
- A – Has A antigens on red blood cells and anti-B antibodies in the plasma.
- B – Has B antigens on red blood cells and anti-A antibodies in the plasma.
- AB – Has both A and B antigens on red blood cells, and no antibodies (universal recipient).
- O – Has no A or B antigens on red blood cells, but has both anti-A and anti-B antibodies in the plasma (universal donor).
Each of these four blood groups is further divided into Rh-positive (+) or Rh-negative (-) based on the presence or absence of the Rh factor (another antigen) on the red blood cells. This gives a total of 8 different blood types:
- A+
- A-
- B+
- B-
- AB+
- AB-
- O+
- O-
How to Know Your Blood Group
To find out your blood group, you need to get a blood test. This test can be done at a hospital, clinic, or a blood donation center. The test involves taking a small sample of blood and mixing it with anti-A, anti-B, and anti-Rh antibodies to see how it reacts. The reactions will reveal your blood type.
Is There an Age Limit to Know Your Blood Group?
No, there is no specific age limit for determining your blood group. Even newborn babies can have their blood group determined at birth through a blood sample. However, blood tests for routine purposes are usually done when a person is older, or when it’s medically necessary.
Which Blood Group is the Rarest?
The rarest blood group is AB-negative (AB-). It is found in less than 1% of the world's population. Here's a rough distribution of blood groups worldwide:
- O+ : 37-40% (most common)
- A+ : 30-32%
- B+ : 10-20%
- AB+ : 3-5%
- O- : 6-8%
- A- : 5-7%
- B- : 1-3%
- AB- : <1% (rarest)
So, if you have AB-, your blood is very rare, and it's important for people with this type to donate if possible, since their blood is in high demand for those in need.