Rh Factor Disease
If you are Rh-negative, you may develop antibodies to a baby that is Rh-positive. (link to Rh factor topic) This is called sensitization and your antibodies can cross the placenta and attach to your baby’s blood cells. They then break down the fetus’s red blood cells and can cause anemia.
Women should have a blood test called an antibody screen done at the beginning of her pregnancy. This identifies the antibodies that develop to red blood cells, like the Rh antibody. If a woman with Rh-negative blood has not been sensitized, her doctor will recommend that she receive RhIg around the 28th week of pregnancy to prevent sensitization for the rest of pregnancy.
If a woman has Rh antibodies, she is considered to be “sensitized.” Usually she will then be seen by a Maternal Fetal Medicine specialist to discuss the risks of fetal anemia, or low blood count. If a woman carries a significant amount of antibodies, then she will be followed with regular ultrasounds. These ultrasounds will look at blood flow within the baby’s brain, which can help predict if the baby is developing anemia. If there is concern for severe anemia, then usually a special type of transfusion will be necessary (called exchange transfusion). This can be done after delivery or through the umbilical cord while the baby is still in the uterus if the pregnancy is too early. If the sensitization is severe, then many times a series of these transfusions may be necessary.
Once the baby is delivered, they will usually be watched for signs of anemia or jaundice. The antibodies will leave the newborns system usually after a couple of weeks, and they will not have any further risk of anemia after this.
Once a woman has been sensitized she will continue to have a risk for anemia in all future pregnancies where the baby is Rh positive.
For further information or to schedule an appointment, please call our Maternal Fetal Care Center at (414) 805-6624.