Rh and ABO Blood Incompatibility During Pregnancy
There are two types of incompatible blood types during pregnancy: Rh incompatibility and ABO blood incompatibility during pregnancy. There are four blood types: A, B, AB, and O. Each blood type may also contain a type of protein called an Rh factor. Those who have it are Rh positive. Those that don’t are Rh negative. So, for example, an individual with type A blood who has the Rh factor is considered A+.
What is Rh incompatibility?
Where it becomes a concern is when the mother is Rh negative but the baby is Rh positive. This incompatibility could result in problems during pregnancy, especially in a woman’s second or subsequent pregnancy. Rh negative blood recognizes the Rh protein on the Rh positive blood cells as being foreign, and builds up antibodies to attack them.
So in the mother’s subsequent pregnancies, these antibodies essentially attack the baby’s blood cells. As a result, it can turn into Rh disease of the newborn (also called hemolytic disease of the newborn, or HDN). In this case, the body can’t keep up with replacing the red blood cells that are destroyed.
There can also be problems while delivering, when the baby and mother’s blood combines and antibodies are produced to attack the foreign substance. Whether it occurs while the baby is in the womb or during delivery, treatment for these conditions will be necessary.
The good news is that this incompatibility can be detected early in the pregnancy. A shot may be administered to the mother during the 28th week of pregnancy and then about 72 hours after delivery.
If antibodies have already developed, the levels will need to be monitored. If they become dangerous, even while still in the womb, the baby could receive an exchange transfusion. This is a blood transfusion that helps to stabilize things. However, it is rarely necessary.
Complications from Rh disease of the newborn can lead to problems in the baby including:
- brain damage;
- severe anemia;
- heart failure;
- jaundice; and
What is ABO Incompatibility?
More common than Rh incompatibility is ABO incompatibility during pregnancy. This occurs when there are incompatible blood types during pregnancy, i.e. the mother’s blood type (A, B, AB or O) is different than the baby’s, which could result in HDN in some cases.
Although jaundice can occur under a variety of circumstances, it may also be present in babies with HDN. Unlike Rh incompatibility, rarely do newborns develop anemia with this type of incompatibility. In fact, ABO incompatibility during pregnancy is generally less serious than Rh incompatibility.
The following are examples of blood types that can result in reactions:
- type O blood reacts against type A, B and AB;
- type A blood reacts against type B and AB; and
- type B blood reacts against type A and AB.
Type AB has no reactions against any of the other blood types. And although type O people can only receive that type of blood with a transfusion, this blood type is known as a universal donor, so it won’t cause a reaction when someone with a type A, B or AB receives it.
Jaundice may not require treatment. However, in some circumstances it could cause complications that require intervention, such as phototherapy, IV fluids, or exchange transfusions.
Left untreated or severe jaundice can lead to a condition called kernicterus, which may cause hearing loss and/or developmental disabilities.