Rh Incompatibility in Pregnancy: Causes, Symptoms, and Treatment

Ever wondered about blood types and how it’s possible to have a completely different blood type from your mother? There are times when different blood types in mother and fetus result in complications during pregnancy. Let’s take a look at the Rhesus factor and the problems that arise because of the incompatibility in blood types.

What does it mean to be Rh incompatibility in pregnancy?

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The 4 basic blood types are A, B, O and AB. Each of these 4 blood types carries a protein known as the Rh factor on the surface of each blood cell. Rh+ means that the Rh factor is present, while Rh- means that it is absent. When the mother is Rh- and the fetus is Rh+, the mother’s body might react adversely to the fetus.

For reasons yet unclear, there are instances in which the fetus’ blood mixes with the mother’s blood. As the fetus’ blood carries antigens not present in the mother’s blood, the mother’s body mistakenly recognizes the fetus as a foreign object and creates antigens to attack the fetus. When these antibodies pass through the placenta and reaches the fetus, they bind with the fetus’ red blood cells and destroys them. This can lead to hemolytic disease of the newborn (HDN) – a blood disorder in which the baby’s red blood cells break down very quickly.

As a result, the baby becomes anemic, and in serious cases, this could result in edema, heart failure (from hydrops, the accumulation of fluid in the tissues) or fetal death. The breaking down of red blood cells creates bilirubin, which is a cause of jaundice in babies after they are born.

If the amount of bilirubin in the baby’s body increases after birth, this can lead to hyperbilirubinemia (too much bilirubin), an enlarged liver and spleen, or jaundice.
In serious cases, increased bilirubin can lead to cerebral palsy or kernicterus (nuclear jaundice) – the condition marked by deposition of bile pigments in the brain and spinal cord – and ultimately result in the fetus’ death.

Rh incompatibility and other types of blood incompatibility

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In addition to Rh incompatibility, there are two other types of blood incompatibility: ABO incompatibility and irregular antibodies.

The mixture of the incompatible blood types of the mother and fetus can lead to placental abruption, syphilis or other infectious diseases, placenta previa, miscarriage or an induced abortion, amniocentesis, preterm labor or preterm birth, or heavy bleeding during delivery.


Rh incompatibility

Blood types are grouped according to the whether the antigen Rhesus is found on the surface or not – hence the terms Rh+ and Rh-. In Rh incompatibility cases, the mother is Rh- and the fetus is Rh+. Unlike the ABO incompatibility, the mother’s body makes antibodies during labor, and though this might not be serious in the first pregnancy, this might worsen in the subsequent pregnancies, resulting in hemolytic disease of the newborn or anemia. If the fetus’ anemia worsens, this could result in a miscarriage or fetal death.

If this is a first-time pregnancy for the mother, the baby is given a shot of anti-D-immunoglobin in the 72 hours after the delivery. As a result, the number of cases of severe jaundice due to Rh incompatibility has decreased.


ABO incompatibility

In most cases of ABO incompatibility, the mother has an O blood type but the baby has an A or B blood type. The UCSF Medical Center reports that ABO incompatibility happens in about less than 15% of pregnancies and though about 3% have hemolytic disease of the newborn (HDN), severe cases make up only 1%.

Babies in cases of ABO incompatibility will have symptoms like slight anemia or jaundice, but ABO incompatibility doesn’t cause fetal death. Jaundice can easily be treated by phototherapy but if the baby’s condition worsens, a blood transfusion might be necessary.


Irregular antibodies

Antibodies apart from the ABO antibodies that are present in red blood cells are termed irregular antibodies. Irregular antibodies are made during a blood transfusion, and if they come into contact with the fetus’ red blood cells through the placenta, this could result in hemolytic disease of the newborn. Rh incompatibility falls under the irregular antibodies category.

Tests for Rh incompatibility

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Even when the baby is at risk of getting HDN, there might be no physical or detectable symptoms in the maternal body. As a result, during the first pregnancy checkup, a blood test will be done. If the mother of the baby is RH- and if the father of the baby is RH+. there will be a need to observe the fetus and do an antibody titer test to check if the mother has been exposed to an antigen (the fetus). The following tests will be conducted:

  • Antibody screen
  • Direct antiglobulin test, also known as the direct Coombs test: Used to test for the presence of antibodies that stick to blood cells and cause them to be destroyed more quickly than usual.
  • Indirect antiglobulin test, also known as the indirect Coombs test: Used to detect non-agglutinating red cell antibodies.
  • Amniocentesis
  • Blood test using fetus’ blood

Rh incompatibility: Treatment of hemolytic disease in newborn

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If the baby is diagnosed with HDN during pregnancy, the main treatment for the baby is a blood transfusion. Other treatments depend on the fetal age of the baby. Treatments like getting rid of the antigen factor in the mother’s blood are also available.

Rh incompatibility doesn’t mean it’s not meant to be

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Even if the mother’s and the fetus’ blood types aren’t compatible, this isn’t a problem if the mother’s body does not create antigens in reaction to the incompatibility. Although receiving treatment in itself is risky, it should be carried out to ensure the baby is as healthy as possible at birth.

If you have a rh baby, don’t be too hard on yourself. This is just an incompatibility in blood types, and you shouldn’t, in any way, interpret it as a rejection of the baby by you or your body. It’s nothing like that, and your baby still has a shot at a healthy life. No self-blame or self-doubt: Your baby is depending on you to give your all.