What is rh sensitization?

You may have Rh-negative blood, and your baby may have Rh-positive blood. If the two types of blood mix, your body will make antibodies. This is called Rh sensitization. In most cases, this isn't a problem the first time you're pregnant. But in future pregnancies, sensitization could cause problems.

If you are already Rh-sensitized or you become Rh-sensitized while pregnant, you won't have any unusual symptoms.

Fetal problems from Rh sensitization are found with Doppler ultrasound testing and sometimes with amniocentesis. A fetus with severe Rh disease may move less often than he or she did earlier in the pregnancy.

There are other conditions with symptoms similar to Rh sensitization. They include fetal infections and other problems where blood types don't mix well.

Anyone who is pregnant will get a blood test at their first prenatal visit to see what their blood type is. If your blood is Rh-negative, it will also be tested for antibodies to Rh-positive blood. This is done with an Rh antibodies screening test or indirect Coombs test. If you have antibodies, it means that you have been sensitized to Rh-positive blood.

If you have Rh-negative blood and are not Rh-sensitized, you will have this test again later in pregnancy.

• The blood test may be repeated between 24 and 28 weeks of pregnancy. If the test still shows that you aren't sensitized, you probably won't need another antibody test until delivery.
• Your baby will have a blood test at birth. If the newborn has Rh-positive blood, you will have an antibody test to see if you were sensitized during late pregnancy or childbirth.

Treatment options depend on how well or poorly the baby is doing. Treatment focuses on preventing or reducing fetal harm and on avoiding early (preterm) delivery.

Treatment is based on how severe the loss of red blood cells (anemia) is.

• If the baby's anemia is mild, you will just have more testing than usual while you are pregnant. The baby may not need any special treatment after birth.
• If anemia is getting worse, it may be safest to deliver the baby early. After delivery, some babies need a blood transfusion or treatment for jaundice.
• For severe anemia, a baby can have a blood transfusion while still in the uterus. This can help keep the baby healthy until he or she is mature enough to be delivered. You may have an early C-section, and the baby may need to have another blood transfusion right after birth.