What are the different blood types?
Everybody has a blood type. There are four major blood groups:
- A
- B
- O
- AB
These groups differ primarily on the presence or absence of antigens that can stimulate an immune response.
In addition to these four groups, a protein called Rh factor that may be either present (+) or absent (-) within each group. This further defines blood groups into eight common types:
- A+
- A-
- B+
- B-
- O+
- O-
- AB+
- AB-
Your blood type is something you inherit, so it’s predetermined at birth. You cannot change your blood type later in life.
How does blood compatibility affect pregnancy?
Compatibility in blood group is only a concern for couples if a pregnancy is involved where both partners are the biological parents. That’s because of RH factor.
Rh factor is an inherited protein, so being Rh negative (-) or Rh positive (+) is determined by your parents. The most common type is Rh positive.
Being Rh positive or negative typically does not affect your health, but it could affect your pregnancy.
Rh factor and pregnancy
Rh factor can be a concern if the biological mother is Rh- and the baby is Rh+. Blood cells from an Rh+ baby crossing its Rh- mother’s bloodstream might trigger an immune response. The mother’s body might form antibodies to attack the baby’s Rh+ red blood cells.
At your first prenatal visit, your doctor will suggest a blood type and Rh factor screening. If you are Rh-, your doctor will test your blood again later in your pregnancy to see if you have formed antibodies against Rh factor. That would indicate that your baby is Rh+.
If your doctor identifies a potential for Rh incompatibility, your pregnancy will be monitored closely for any related issues and may need extra care.
Although your blood and your baby’s blood typically do not mix during pregnancy, a minimal amount of your baby’s blood and your blood could come in contact with each other during delivery. If there’s an Rh incompatibility and this happens, your body might produce Rh antibodies against Rh factor.
These antibodies will not cause problems to an Rh+ baby during the first pregnancy. But they can cause issues if you have a subsequent pregnancy and are carrying another child that is Rh+.
If there was an Rh incompatibility in a first pregnancy, and there’s an Rh incompatibility in second and other future pregnancies, these maternal antibodies can damage the baby’s red blood cells. If this occurs, your baby might need a red blood cell transfusion either during your pregnancy or immediately after delivery.
How is Rh incompatibility treated?
If Rh incompatibility has been diagnosed, your doctor will most likely recommend Rh immune globulin (RhoGAM) in your seventh month of pregnancy, and then again within 72 hours after delivery if your baby’s blood type is confirmed as Rh positive upon delivery.
Rh immune globulin contains Rh IgG antibody, so your body does not react to your baby’s Rh positive cells as if they were a foreign substance, and your body will not produce its own Rh antibodies.
