The Rh factor is the name of a protein often found on the surface of red blood cells. It is identified as part of your early obstetrical blood panel. It is important to know your Rh status because it determines if your blood type is compatible with your growing baby’s blood type. Most problems described below only apply if you are Rh negative.
Your baby’s Rh status will passed down genetically from either you or the father of your baby. There is no incompatibility problem unless you are Rh negative and your baby is Rh positive. All other Rh combinations are fine. About 9 out of 10 women are “Rh positive” and the remainder are “Rh negative.”
If you are Rh negative, the father of your baby will be tested. If he is also Rh negative, you have nothing to worry about. If he, on the other hand, is Rh positive, then the baby might be Rh positive as well.
If this is the case, your immune system will think that the Rh protein on the baby’s blood cell surface is foreign, and your immune system will subsequently start destroying your baby’s blood cells. Sometime this process can be very harmful to your baby.
Fortunately, your body’s immune system needs to be exposed to the new Rh protein for a long time before an immune response occurs in your body against the baby.
Since your baby’s blood circulation is separate from yours, your immune system will only be exposed to the foreign Rh protein when your blood mixes. This can occur during any episode of bleeding in your pregnancy or during the delivery process.
A very effective way to prevent your immune system from building “attack proteins” against your baby and future babies is for you to receive an injection with Rh Immune Globulin, often called Rhogam®.
Rhogam® is an immune protein that will stick to the Rh proteins on the baby’s red blood cells if found in your blood stream. By doing this, it will “hide” them from your immune system. No exposure occurs and your body will therefore not mount an immune response to it.
You will be given Rhogam® if you bleed for any reason in the beginning of your pregnancy. You will also be given Rhogam® during the beginning of the third trimester (28 to 32 weeks) to cover for any bleeding that might potentially occur during the last trimester. Finally, you will be given Rhogam® after the birth if your baby is Rh positive.