Pregnancy Issues: Rh Negative Factor

During pregnancy, the RH factor comes into play. The doctor will order a blood test early in pregnancy to find out which the blood type the patient is. Most women are RH + which there are no worries for incompatibilty. If the patient is RH-, then the doctor will give a Rhogam shot at 28 weeks gestation and again within 72 hours of birth if the child is Rh positive. Why is this so important? Complications can arise if the RH factor is not addressed.

What is RH-

'The Rh system was named after rhesus monkeys, since they were initially used in the research to make the antiserum for typing blood samples. If the antiserum agglutinates your red cells, you are Rh+ . If it doesn't, you are Rh- . It is only when the two blood types are mingled in an Rh-negative individual that the difficulty arises, since the Rh factor acts as an antigen in Rh-negative persons, causing the production of antibodies.

Besides the Rh factor, human red blood cells contain a large number of additional antigenic substances that have been classified into many blood group systems (see blood groups); however, the Rh system is the only one, aside from the ABO system, that is of major importance in blood transfusions. If Rh-positive blood is transfused into an Rh-negative person, the latter will gradually develop antibodies called anti-Rh agglutinins, that attach to the Rh-positive red blood cells, causing them to agglutinate. Destruction of the cells (hemolysis) eventually results.

If the Rh-negative recipient is given additional transfusions of Rh-positive blood, the concentration of anti-Rh agglutinins may become high enough to cause a serious or fatal reaction. The same type of immune reaction occurs in the blood of an Rh-negative mother who is carrying an Rh-positive fetus. (The probability of this situation occurring is high if the father is Rh positive.) Some of the infant's blood may enter the maternal circulation, causing the formation of agglutinins against the fetal red blood cells.

Note: The first baby is usually not harmed. But, if the mother's agglutinins pass into the circulation of subsequent fetuses, they may destroy the fetal red blood cells, causing' complications between mother and unborn baby.

What may happen if the shot is not given:

'Rh disease can result in severe anemia, jaundice, brain damage, and heart failure in a newborn. In extreme cases, it can cause the death of the fetus because too many red blood cells have been depleted.' Other complications that may arise: neurological syndrome with mental deficiency, movement disorder, hearing loss, speech disorder, and seizures.

  • Erythroblastosis Fetalis or Hemolytic Disease
  • hemolytic comes from two words: hemo (blood) and lysis (destruction) or breaking down of red blood cells
  • erythroblastosis refers to the making of immature red blood cells
  • fetalis refers to the fetus

Checklist to ensure RH compatibility:

  • ♥Accurate Blood Test
  • ♥Rhogam shot at 28 weeks gestation and again within 72 hours of birth
  • ♥Follow your intuition. If you feel your blood test is not correct, you may ask your doctor to do another one and send it through a different lab.

For more detailed information, please check out the reference listed below.


  • Danielsson, Krissi (2008). Did My Miscarriage Happen Because I'm Rh Negative?. Retrieved February 9, 2009, from Web site

  • O'Neil, Dennis (2009). Rh Blood Types. Retrieved February 9, 2009, from Human Blood Web site

  • Rh factor. (2008). Retrieved February 9, 2009, from Infoplease Web site

  • Weiss, Robin Elise (2009). Rh Factor in Pregnancy. Retrieved February 9, 2009, from Web site

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