How Does Rh-Negative Affect Pregnancy?

Medically Reviewed on 5/12/2022
How does Rh-negative affect pregnancy?
During pregnancy, an Rh-negative woman develops the risk of Rh incompatibility.

Rh factor is a protein present on the surface of the blood cells. The presence of the Rh factor on blood cells deems a person an Rh-positive person, whereas the absence of the factor makes an Rh-negative individual.

The factor plays an important role in compatibility, especially during pregnancy if the mother is an Rh-negative individual and the fetus is Rh-positive. The Rh factor is inherited from either of the parents, and the mismatch of the Rh factor leads to a condition called Rh blood incompatibility.

How to test for Rh incompatibility

Simple blood tests can efficiently diagnose the possibility of having Rh incompatibility conditions in the future. This is usually done during the routine first-trimester checkup.

  • Rh-negative mothers are checked for Rh incompatibility through antibody screening. This test helps assess if the mother’s blood has Rh antibodies.
  • If the antibody screening comes back positive, then the mother is at risk of developing Rh incompatibility.
  • In the case of a negative result, the mother is administered Rh immunoglobulin, which will prevent antibody formation.

If the mother suffers from bleeding or other complications during the first few months of pregnancy, then the Rh immunoglobulin can be administered about 28 weeks or earlier. Otherwise, it can be administered within 72 hours of delivery as well.

Who develops the risk of Rh incompatibility?

During pregnancy, an Rh-negative woman develops the risk of Rh incompatibility. Statistically, 85 percent of individuals in the world are Rh-positive. Because the Rh factor is inherited from either of the parents, the risk can increase greatly if the father of the baby is an Rh-positive individual.

When an Rh-negative person conceives a baby with an Rh-positive person, the baby could be Rh-positive or Rh-negative. If the baby is Rh-negative, that causes no problems. The problems start if the baby is Rh-positive.

  • If this is the first pregnancy, there is generally no complication. The blood circulatory system of mother and baby are distinct from one another. Thus, ideally, the blood of the baby and mother should not come in contact.
  • The only chance when the blood may come together is during delivery when the placenta separates. During this time, even if little blood (Rh positive) from the baby comes in contact with the Rh-negative mother, the mother’s blood develops antibodies against this blood for the lifetime.

During the second pregnancy, if the baby is Rh-negative, there are no consequences. However, if the second baby is Rh-negative and the blood from the mother comes in contact with the fetal blood (during diagnostic procedures in pregnancy, intrauterine placental separation), the maternal antibodies attack fetal blood and generate a severe reaction in both mother and child.


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Effects of Rh-negative pregnancy

Rh incompatibility does not affect the pregnant women, but for the growing fetus, it can lead to complications, such as hemolytic anemia, heart failure, or intrauterine death.

The baby’s red blood cells get destroyed faster than they can be replaced, which can cause mild to severe health conditions in the baby.

As the red blood cells carry oxygen through the body, the condition inhibits oxygen transport, and the baby can be affected with jaundice, liver failure, and, in some cases, can cause heart failure.

Rh incompatibility does not necessarily mean that it will pose a threat to the fetus.

Treatment and prevention

Medical professionals treat the condition depending on the severity of the condition. For mild cases of hemolytic anemia, no treatments are prescribed. However, for severe conditions, the baby can receive blood transfusion through the umbilical cord, which replaces the baby’s red blood cells.

For babies affected with jaundice and who have high levels of bilirubin in the blood, they are treated with special lights that reduce the bilirubin levels.

Certain preventative measures can be employed to prevent the detrimental effects of Rh incompatibility. Administration of Rh immunoglobulin can prevent the development of Rh antibodies.

Fluid buildup leads to fetal jaundice. Regular antibody screening during pregnancies can help avoid such conditions. Treatments, such as early delivery, exchange transfusion, and phototherapy, can be administered to the baby to prevent complications arising from Rh incompatibility.

Rh incompatibility is a rare condition during pregnancy and with effective treatment and early diagnosis, any harm to the growing fetus can be prevented.

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Medically Reviewed on 5/12/2022
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Medline Plus. Rh incompatibility.

American Pregnancy Association. Rh Factor Blood Type and Pregnancy.