Regional Medical Laboratory

Do I need Rho(D) Immune Globulin?

Any person with a blood type of Rho- (D negative) your body may produce an immune response or defense against Rho+ (D positive) blood. If you’re a pregnant woman who is Rho- (D negative) and your baby's blood type is Rho+ (D positive), your body may produce the same defense against your baby’s blood. The immune response is a production of red blood cell antibodies specific for Rho+ (D positive) red cells.

These antibodies usually will not cause a problem if this is your first pregnancy. However, if you have other Rho+ (D positive) babies in the future, these antibodies may try to destroy the blood of the future babies. If this occurs, it is a very serious condition. Babies born with this condition may need to have their blood replaced.

Rho(D) immune globulin is used to help prevent your body from starting that defense to any of your baby's Rho+ (D positive) blood that may get into your blood system while you are pregnant or during the delivery of your baby. Rho(D) immune globulin is given at certain times during your pregnancy as insurance against this immune response to Rho+ (D positive) blood cells. Once injected around the 27-28 week of gestation, the Rho(D) immune globulin should continue to circulate in the mothers blood stream until delivery.

Unfortunately we cannot determine the Rho(D) status of the baby until it is born. After the delivery of the child, testing will be performed on the cord blood to determine if the baby is Rho+ (D positive) or Rho- (D negative). If the baby is Rho+ (D positive) additional testing is performed on the mother to determine the amount of the baby's blood flowing in the mothers circulation. This will determine the amount of Rho(D) immune globulin that is to be given to the mother. In most cases a single standard dose given within 72hrs of delivery is sufficient to prevent an immune response.