Knowing one’s blood type is important for a variety of reasons. The first is that in an accident, if one loses enough blood to require a transfusion, one can become severely ill if blood of the wrong type is administered. Fortunately hospitals usually do a quick blood type test to avoid transfusing incompatible blood.

Prior to any surgery, blood is usually typed. Blood type tests also used to be standard requirements prior to obtaining a marriage certificate in most states. This is no longer standard procedure in many states, but the reasons for requiring it were solid.

If a woman has a blood type that is negative and she conceives a child with a man with a positive blood type, the results can be devastating. Generally the first child conceived will be fine if the child has a positive blood type. However the second child can develop what is called RH disease, and may be severely affected by the mother’s negative RH factor.

The body can produce antibodies, which attack the growing unborn child with a variety of results. In a sense, the mother’s body is allergic to the baby’s blood type. For this reason, women who have a negative RH are given a vaccine after the birth of their first child, which can prevent such a reaction. This does not work in the opposite direction. A woman with a positive blood type can have a child with a negative blood type with no adverse reaction.

Knowing one’s blood type can also be important because there is a constant need for blood donations. Certain rare blood types have access to less supply than the most typical O positive blood type. Being O negative is of great asset to one’s community since one is considered a universal donor. In all cases that do not require type specific blood, O negative blood is acceptable for transfusions.

Since O negative blood is fairly rare, those who possess this type can really serve their community by donating blood on a frequent basis. Other blood types in high demand are AB, A, and B, both positive and negative. Sometimes people can only have transfusions that are specific to their blood type. So less common types really help everyone around them by being frequent donors.

Blood typing can also be an important first step to becoming a bone marrow donor. In general, the more rare one’s blood type, the more likely one could donate bone marrow and help save someone’s life. In the US, blood and bone marrow donations are particularly needed for those of Asian, Hispanic, and African-American descent.

These groups have a smaller population from which to draw than the Caucasian population. Thus they have more difficulty obtaining bone marrow. If one has a rare blood type, one should consider the possibility of becoming a bone marrow donor. Though there are no monetary rewards for such, the emotional rewards of saving someone’s life can be quite significant.