Rh Factor And Rhogam Shots

Terms like Rh-positive and Rh-negative sound more of mathematical terms than baby biology and mathematics is the last thing you, with your fuddled pregnancy brain, could want to think about. However, these terms have nothing to do with mathematics in any way; rather, they refer to specific biological aspects. As such, it is important to understand what Rh factor is and what it is all about.

What is Rh-Factor?

Just like there are many different blood groups like type A, AB and so on, there also is the Rh factor. This factor is, in specifics, a protein that is present on the surface of a healthy persons red blood cells. It is interesting to note that this factor can either be present or absent in a person. As such, people who have it are Rh positive while those who do not have it are Rh negative.

The Rh factor is hereditary – meaning that it is inherited by children from their parent’s genes. If the father is Rh+ and the mother is Rh-, there is very high chance the fetus will inherit its Rh genes from the father and could therefore be either Rh+ or Rh-. However, in the event both the father and mother are Rh negative, then the baby will end up being Rh negative.

Rh-Factor and Pregnancy

When it comes to pregnancy, the Rh factor plays a major role and could cause problems if you, the mother, are Rh negative, and the fetus is Rh positive. This scenario is normally referred to as Rh incompatibility and often the problems will not be noticed during the first pregnancy but rather in subsequent pregnancies.

When the mother and the fetus are incompatible that is, the mother is negative while the fetus is Rh positive, then a couple of things start taking place. When the mother’s blood mixes with that of her Rh+ fetus, it causes her Rh negative to create antibodies against the fetus’ Rh factor. The antibodies then attack the fetus’s Rh factor as though it were something harmful. Such a person one who’s Rh negative and whose system can create Rh antibodies – is referred to as Rh Sensitized.

How Rh Sensitization Occurs

When pregnant, the mother and the fetus don’t share their blood systems. Nevertheless, a small amount of the fetus’ blood can or may cross the mother’s placenta and into her system – this happens during either pregnancy, labor or birth. It also may happen if a mother who is Rh negative experiences the following at any point during her pregnancy:

  • Bleeding during pregnancy
  • Amniocentesis
  • The manual rotation of the baby during a breech presentation just before labor
  • Chorionic villus sampling
  • Blunt trauma to the mother’s abdomen during her pregnancy

Often, during a Rh- woman’s first pregnancy of a Rh+ fetus, the problems are never too serious as the baby is born before her body can develop many antibodies. However, if no preventive treatment is undertaken during the woman’s first pregnancy, there is a very high risk that her later pregnancy with an Rh+ fetus could put the baby at risk of being attacked by Rh disease.

Rh Sensitization And Its Effect On The Fetus

Rh sensitization can be harmful to the fetus; especially when Rh antibodies from a Rh sensitized woman cross into the placenta and starts attacking the blood of the fetus. These antibodies start destroying some of the fetus’ red blood cells causing hemolytic anemia where the red blood cells are getting destroyed faster than they can be replaced by the body. Severe hemolytic anemia can be fatal to the developing fetus.

Rh Sensitization Testing And Prevention

If you are Rh negative and are pregnant with a Rh positive baby, it is important that you get antibody screen blood test to see if your body is developing or has developed any antibodies to Rh+ blood and how many of these antibodies have been made. It is advisable that this test be done during the first trimester and once again during the 28th week of pregnancy.

The great thing is that, if detected early enough, Rh sensitization can be prevented. As such, if you are negative, then an Rhlg or Rh immunoglobulin shot is administered. When this immunoglobulin is administered to a nonsensitized Rh- person, it goes to target any Rh+ cells in their bloodstream, preventing the production of any Rh antibodies. When administered in a woman who’s Rh-negative and has not yet made any antibodies against the Rh+ factor, the immunoglobulin could help prevent against hemolytic anemia in the fetus later in the pregnancy.

Rhogam Shots and Your Pregnancy

Rhogam is an Rh Immunoglobulin vaccine designed to help keep the blood of Rh negative women from attacking their Rh positive fetuses. However, this vaccine-like compound can only be effective if the mother has not yet become Rh sensitized. That is why it is important that the mother have her blood tested early in time to find out if she is Rh negative and if her system is developing any antibodies against her fetus.

The best time to do this is during the first trimester of your first pregnancy. It is during this time, that any abnormalities can easily be identified. Once identified, the Rhogam shot will be administered during the 28th week of your pregnancy and once again within 72 hours after you have given birth. This ensures that all subsequent pregnancies will be safe as the first and that you do not grow Rh sensitized. Other times the Rhogam shot will be administered is after chorionic villus sampling or amniocentesis, miscarriage, ectopic pregnancy, or abortion.