The Rh factor is one of many blood group components found on the surface of red blood cells. If you have this component, you are Rh positive and if not, you are Rh negative. This information is important if you are a pregnant woman who is Rh negative. If you are Rh negative and the baby’s father is Rh positive, chances are that the baby will also be Rh positive.
What is the concern with an Rh negative mother and Rh positive baby?
If some of the baby’s Rh positive red blood cells enter your Rh negative bloodstream, an immune reaction could occur. When an immune reaction occurs, it means that your defense system recognizes the Rh positive blood cells as foreign, and it produces antibodies which destroy the “invading” foreign cells.
These antibodies to Rh positive cells may not be a problem in a first pregnancy, but they stay in your body for many years and may be a problem in future pregnancies. They may cause miscarriage or a disease in the newborn that breaks down the baby’s red blood cells (Hemolytic Disease of the Newborn).
How does Rh positive blood enter the bloodstream of an Rh negative woman?
The passage of blood from baby to mother can happen at delivery, during miscarriage, as a result of termination of pregnancy, during amniocentesis (a genetic test), or due to trauma.
How is the risk prevented?
To prevent this problem, you will be given an injection of either Rho Immune Globulin (Rho Gam) or Rhophylac. These injections destroy any Rh positive cells which may enter your bloodstream and prevents the immune system from setting up its normal response to these foreign cells, thus protecting the baby.
Your blood type was determined when blood was drawn during your first visit for your pregnancy. If you are Rh negative you will receive a Rho Gam or Rhophylac injection at your 28-week visit.
At delivery, a sample of the baby’s blood will be collected and tested. If your baby is Rh positive, you will receive another injection before leaving the hospital.
You should receive Rho Gam or Rhophylac during each pregnancy, with miscarriage or termination of pregnancy, amniocentesis or with any trauma which your physician feels could cause bleeding in the uterus.