Your Blood: What You Should Know Before Pregnancy and Child Birth

your blood
Credit: essentialbaby

What does your blood contain?

The Blood is the red fluid that circulates in the blood vessels. i.e. veins and arteries. It plays a major role in the body’s defense against infection. It has four main components which are: red blood cell, white blood cell, plasma, and platelets.


There are four different blood types. Every individual possess   one of the four different blood types and these blood types are classified based on the kind of antigen that is present on the surface of the red blood cell.

Antigens: these are protein molecules that are found on the surface of red blood cells. They help the body differentiate between its own cells and foreign cells, potentially dangerous ones. While antibodies are protein found in the plasma. They recognize foreign substances in the body and alert the immune system to destroy them.

The blood types are:

  • Type A which has the A antigen
  • Type B which has the B antigen
  • Type AB which has both A and B antigens
  • Type O which has neither A or B antigens.

When blood enters a system with antigens that is not present in that system, the body will create antibodies against it. As a result of this, a person with type O blood can donate blood to anyone (because their blood has no antigens) but can ONLY receive blood from type O.

Type A individuals can donate blood to other type A and type AB individuals but can only receive blood from type A and type O individuals. The same thing goes for type B who can ONLY receive from type B and type O individuals but can donate to type B and type AB. For type AB individuals, they can donate blood to ONLY type AB individuals, but can receive blood of any type.


  • In case of blood transfusion: Blood transfusion is the process of receiving blood or blood products into one’s circulation intravenously. The recipient’s blood is tested against the donor’s cells to ensure that the recipient is given blood that is compatible and is as safe as possible. Also to prevent severe acute hemolytic reaction, renal failure which is likely to occur with death being a possibility, it is important that we know our blood type.
  • In pregnancy: Pregnant mothers are usually advised to undergo a blood test. This is because a woman who is rhesus (Rh) D negative and married to a man who is Rh D positive will most likely have a Rh D positive child which was inherited from the father and this if left untreated, can result in complications.
  • To prevent ABO incompatibility reaction: ABO incompatibility reaction occurs when you receive the wrong type of blood during a blood transfusion. It is a serious and potentially fatal response by your immune system to incompatible blood. Your immune system produces antibodies against any blood antigens that is not present in your own blood. This therefore means that people with type A blood create antibodies against B antigens. A person with type A blood receiving a transfusion of type B or AB would lead to an ABO incompatibility reaction. In this reaction, your immune system attacks the new blood cells and destroys them. Hence, a type A person can receive blood ONLY from another type A.


Rhesus factor is a protein that is present on the surface of red blood cells. Those with Rh factor on their red blood cells are said to be Rh positive while those without the Rh factor are said to be Rh negative. The Rh factor is passed from parents to their offspring’s. The Rh factor can however, cause problems during pregnancy if the mother is Rh negative and the fetus is Rh positive. This is called RH incompatibility. This problem usually does not occur with first pregnancy but, it however occurs in subsequent pregnancies of Rh negative woman where the fetus is RH positive, leading to Rh positive pregnancy.


During pregnancy, a small amount of the baby’s blood can enter the mother’s circulation. If the mother is Rh negative and the baby is Rh positive, the mother will produce antibodies (including IgG) against the Rh D antigen on her baby’s red blood cells. The baby is however, not affected at first pregnancy because the mother’s antibodies have not developed fully. At subsequent pregnancies when the mother’s antibodies have been fully developed, the IgG is able to pass through the placenta into the fetus causing destruction of RH D positive fetal red blood cells leading to the development of Rh disease. This disease becomes worse with additional Rh incompatible pregnancy.


Rh incompatibility can be prevented by administering treatment to the mother during pregnancy or promptly within 72hrs after child birth. The mother is injected intramuscularly with anti-Rh antibodies (Rho (D) immunoglobulin). This is done so that the fetal Rh D positive red blood cells are destroyed before her immune system discovers them.





  1. American blood group
  2. Bowman, J.; chown, B.; Lewis, M.; Pollock, J.M (1978). “Rh immunization during pregnancy: antenatal prophylaxis”. Canadian Med Ass Journal 118 (6): 623-627 PMC 1818025 PMD 77714
  3. Mc Bain, RD, Crowther, CA; Middleton, P (3September 2015). “Anti-D administration in pregnancy for Rhesus alloimmunization”. The Cochrane data base of systematic reviews. 9: CD 000020. PMID 26334436.
  4. Janatpour, K.A, Kalin, N.D, Jensen, H.M, and Holland, P.V (2008). Clinical outcomes of ABO incompatible RBC transfusion. American Journal of clinical pathology.

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