Rh Sensitization During Pregnancy
What is Rh sensitization during pregnancy?
If you are Rh-negative, your red blood cells do not have a marker called Rh factor on them. Rh-positive blood does have this marker. If your blood mixes with Rh-positive blood, your immune system will react to the Rh factor by making antibodies to destroy it. This immune system response is called Rh sensitization.
What causes Rh sensitization during pregnancy?
Rh sensitization can occur during pregnancy if you are Rh-negative and pregnant with a developing baby (fetus) who has Rh-positive blood. In most cases, your blood will not mix with your baby's blood until delivery. It takes a while to make antibodies that can affect the baby, so during your first pregnancy, the baby probably would not be affected.
But if you get pregnant again with an Rh-positive baby, the antibodies already in your blood could attack the baby's red blood cells. This can cause the baby to have anemia, jaundice, or more serious problems. This is called Rh disease. The problems will tend to get worse with each Rh-positive pregnancy you have.
Rh sensitization is one reason it's important to see your doctor in the first trimester of pregnancy. It doesn't cause any warning symptoms, and a blood test is the only way to know you have it or are at risk for it.
Who gets Rh sensitization during pregnancy?
Rh sensitization during pregnancy can only happen if a woman has Rh-negative blood and only if her baby has Rh-positive blood.
If you have Rh-negative blood, your doctor will probably treat you as though the baby's blood is Rh-positive no matter what the father's blood type is, just to be on the safe side.
How is Rh sensitization diagnosed?
All pregnant women get a blood test at their first prenatal visit during early pregnancy. This test will show if you have Rh-negative blood and if you are Rh-sensitized.
If you have Rh-negative blood but are not sensitized:
If you are Rh-sensitized, your doctor will watch your pregnancy carefully. You may have:
How is Rh sensitization prevented?
If you have Rh-negative blood but are not Rh-sensitized, your doctor will give you one or more shots of Rh immune globulin (such as RhoGAM). This prevents Rh sensitization in about 99 women out of 100 who use it.1
You may get a shot of Rh immune globulin:
The shots only work for a short time, so you will need to repeat this treatment each time you get pregnant. (To prevent sensitization in future pregnancies, Rh immune globulin is also given when an Rh-negative woman has a miscarriage, abortion, or ectopic pregnancy.)
The shots won't work if you are already Rh-sensitized.
How is it treated?
If you are Rh-sensitized, you will have regular testing to see how your baby is doing. You may also need to see a doctor who specializes in high-risk pregnancies (a perinatologist).
Treatment of the baby is based on how severe the loss of red blood cells (anemia) is.
In the past, Rh sensitization was often deadly for the baby. But improved testing and treatment mean that now most babies with Rh disease survive and do well after birth.
Frequently Asked Questions
eMedicineHealth Medical Reference from Healthwise
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