Explainer: Why you need to know your blood group

Do you know your blood type? Even though blood type tests are simple and accessible, many people are not aware of their blood types.

There are four blood groups A, B, AB and O. These blood groups refer to the presence of different antigens on the red blood cell. Those whose blood group is AB have both and B antigens on their red blood cells. If you have blood group O, you have neither A or B antigens.

There’s an additional antigen, D. People with this antigen are Rhesus D positive. Those who lack the D antigen are said to be RhD negative. The suffix (such as A+ or B-) in blood types usually indicates the presence or absence of the D antigen.

1. Blood transfusion

Blood transfusions with the wrong blood type can be catastrophic or even fatal. Receiving incompatible blood type can cause the recipient’s blood to clump, which can quickly become fatal. Therefore, testing the blood type of recipients and donors can’t be over-emphasised.

But other than transfusion, your blood group has other implications on your health. Although the medical community used to dismiss the idea, recent studies have shown that there could be a link between blood groups and certain health conditions.

2. Cardiovascular Disease

People with blood group O have a reduced risk of suffering from coronary heart disease (CHD). In a 2012 study published in the journal Arteriosclerosis Thrombosis, and Vascular Biology, researchers identified blood type as a significant factor for developing coronary heart disease. They found that blood groups A, B, and AB had a respective 5,11, and 23 percent higher risk of developing CHD than those with O blood type. 

3. Blood Clots

If you have blood type A, B, or AB, you have higher risk of having deep vein thrombosis – life-threatening blood clots in the legs that can travel up to your lungs. Danish researchers analysed data on about 66,000 people over more than 30 years and found that people with AB, A, and B blood types had a 40 per cent higher risk of developing DVT than those with O blood type.

On further research, the scientists found that people with AB blood type contributed to about 20 per cent of blood clots. Genetic mutations accounted for 11 per cent, being overweight explained 16 per cent, while smoking could be linked to 6 per cent of blood clots.

4. Stomach Cancer

If you have blood type A or AB, you might be at a higher risk of developing stomach cancer. In a 2019 study published in BMC Cancer, researchers using genetic data from cases and controls found a link between these blood types and gastric cancer in Chinese populations. Additionally, a review of 39 previous studies confirmed their findings.

5. Fertility

Are you struggling with infertility? If you have blood type O, it might have something to do with it. According to a study published in Human Reproduction, women with this blood type were twice as likely to have high levels of FSH hormones which indicate low ovarian reserve and therefore low fertility.

6. Dementia and memory loss

Do you have blood group AB? The bad news is that you have an 82 per cent higher risk of cognitive decline in later life than those with other blood types. According to a study published in Neurology, this could be because people with AB blood type have larger amounts of Factor VIII proteins which help with blood clotting. Study participants with Factor VIII proteins were found to have 24 per cent higher risk of developing memory problems regardless of their blood type as compared to other blood types.

7. Blood type and pregnancy

When you find out that you’re pregnant, one of the first tests that your doctor will order for is a blood type test. Determining a pregnant woman’s blood type, especially the presence of the Rhesus (Rh) factor is important. If a mother who is Rh- is carrying a Rh+ baby, the mother’s body can build antibodies against the baby’s blood type. Fortunately, this might not cause any problems in the first pregnancy. However, it could cause miscarriages later.