RhoGAM ® or Rho(D) immune globulin is a sterilized solution made from human blood that contains antibodies to the Rh factor. The Rh factor is a type of protein on the surface of the red blood cell. Most people have the Rh factor in their blood (Rh-positive) but some people do not (Rh-negative). During pregnancy, problems can arise when the mother is Rh-negative and the fetus's blood has the Rh factor, inherited from the father. When a woman with Rh-negative blood is exposed to Rh-positive fetal blood, the body begins to develop antibodies in response to the Rh antigens in the fetus’ blood. This process is known as sensitization.
A woman who is Rh-negative can become sensitized during pregnancy if she is exposed to Rh-positive blood from the fetus. Women are most likely to be exposed to the fetus’ blood during the last three months of pregnancy and at delivery. Therefore, during pregnancy women are usually given a dose of RhoGAM® at approximately 28 weeks gestation and then receive another dose within 72 hours of birth, if the baby has an Rh- positive blood type. The physician may prescribe additional doses of RhoGAM after an amniocentesis, abdominal trauma or other event that may result in exposure to fetal blood at any time during the pregnancy. In addition women need to be considered exposed to fetal blood after a miscarriage and should be considered a candidate for RhoGAM.
Treatment with RhoGAM is only good for the pregnancy in which it is given. Each pregnancy and delivery of an Rh-positive child requires repeat doses of RhoGAM.