Can It Be Prevented?
A simple blood test can reveal whether or not you have Rh-negative blood. Every woman should be tested early in pregnancy, or prior to pregnancy, to find out. To prevent Rh disease, an Rh-negative woman should receive an injection of Rh immunoglobulin (RhIg) within 72 hours of delivering an Rh-positive baby. This prevents sensitization in more than 95 percent of Rh-negative women. However, studies show that about 2 percent of pregnant women become sensitized prior to delivery. For this reason, an RhIg injection is given around the 28th week of pregnancy as well.
The RhIg treatment must be repeated with each pregnancy, miscarriage, abortion, and blood transfusion with Rh-positive blood, and after amniocentesis (a procedure in which a needle is inserted into the uterus to obtain a small sample of amniotic fluid) or another prenatal test called chorionic villus sampling (CVS).
Unfortunately, RhIg will not work for an Rh-negative woman who has already been sensitized (her body has produced antibodies to Rh-positive cells) by a prior pregnancy, miscarriage, abortion, or transfusion.