Rh Incompatibility

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KEY POINTS

• Having Rh incompatibility when you are pregnant means that there is a protein on the surface of your baby's red blood cells that is not on your blood cells.
• Shots of Rh immune globulin (RhIg) can stop your body from making antibodies to the Rh factor. If you are Rh negative, you should have the RhIg shot any time that your baby's blood could leak into your system.
• If you think you may be pregnant, see your healthcare provider. Tests can show if the Rh factor could be a problem, and RhIg shots can prevent problems for your baby.

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What is Rh incompatibility?

Having Rh incompatibility when you are pregnant means that there is a protein on the surface of your baby's red blood cells that is not on your blood cells. This protein is called the Rh factor. People who have the Rh factor are Rh positive. People who do not have it are Rh negative. Rh incompatibility happens only if you are Rh negative and your baby is Rh positive.

You have probably been told that your blood type is A, B, AB, or O, and positive or negative. For example, your blood type might be A positive or A negative. The positive or negative part of the blood type refers to your blood’s Rh factor.

What is the cause?

Being Rh negative or positive is something you inherit from your parents. If you are Rh negative and the baby's father is Rh positive, your baby could have either type of blood.

If you are Rh negative and your baby is Rh positive, your body makes antibodies to the Rh factor when it comes in contact with your baby’s red blood cells. Antibodies are the proteins your immune system makes to fight infections, such as the flu and measles. Your body usually does not start making antibodies to the Rh factor until after the birth of an Rh-positive baby. This means that Rh incompatibility is usually not a problem with your first Rh-positive baby. However, later pregnancies and deliveries might be affected unless you are treated for Rh incompatibility. The antibodies could come in contact with your baby's blood and destroy his normal, healthy red blood cells. The destruction of red blood cells can cause serious problems for your baby, including death.

What are the symptoms?

You will not have any symptoms, but your baby will. When your baby is born, your baby may have yellow eyes and skin (jaundice), swelling, and breathing problems. The baby might die in the womb if too much of his blood is destroyed by the antibodies.

How is it diagnosed?

Blood tests can show if you are Rh positive or negative. Blood tests also check for antibodies against the Rh factor. If you are Rh negative, your baby's father should also be tested. If both you and the father are Rh negative, there will not be a problem because your baby will also be Rh negative.

Some of the tests used to check your baby are:

• Amniocentesis, which uses a very thin needle to remove a small amount of fluid from the amniotic sac
• Cordocentesis, which uses a very thin needle to remove a small amount of blood from the baby’s umbilical cord
• Ultrasound scan, which uses sound waves to show pictures of the baby
• Nonstress test, which uses a monitor attached with belts to your belly to record how your baby's heart rate changes when the baby moves
• Blood tests

How is it treated?

Shots of Rh immune globulin (RhIg) can stop your body from making antibodies to the Rh factor. If you are Rh negative, you should have the RhIg shot any time that your baby's blood could leak into your system. This includes:

• During or after all pregnancies, including tubal pregnancies. The shot may be given at about 28 weeks of pregnancy. For added protection, you will have a second shot after your baby is born. The shot may also be given for the first time within 72 hours after your baby is born.
• After a miscarriage or abortion. If you almost had a miscarriage but did not actually miscarry, you may still need a RhIg shot.
• After bleeding during the pregnancy
• After pregnancy tests, such as amniocentesis
• After a procedure done to change your baby's position before birth
• After an injury to your belly
• After problems with the placenta, like when your placenta is too low in your womb or pulls away from the wall of your uterus

If your baby may have problems before birth, you may be referred to a specialist to help manage your pregnancy. Your baby may need a blood transfusion before birth. Sometimes the baby needs to be delivered early with a C-section.

How can I help prevent the problems caused by Rh incompatibility?

If you think you may be pregnant, see your healthcare provider. Tests can show if the Rh factor could be a problem, and RhIg shots can prevent problems for your baby.