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Negative Blood Group and Pregnancy Rh Incompatibility

Published on Jan 03, 2017 and last reviewed on Mar 23, 2022   -  5 min read

Abstract

This article briefly describes the Rh-negative blood group, associated pregnancy complications, and preventions in simple terms.

Contents
Negative Blood Group and Pregnancy Rh Incompatibility

What Is the Rh Factor?

There are mainly four blood groups, namely A, B, O, and AB. There is a subtype of each as positive and negative blood groups, namely A +ve, A -ve, B +ve, B -ve, etc. The subtype gets decided by the Rh factor (rhesus), an antigen present on the red blood cells. When it is present, it is a positive blood group, whereas if it is absent, it is defined as a negative blood group. In simpler terms, the positive or negative symbol that accompanies your type of blood group is called the Rh factor.

In the general public, the absence of this antigen does not cause any issues. But, if an Rh-negative mother is carrying an Rh-positive baby, there is a need to take special care and treatment and some precautions and preventive measures.

There is a mixing of the mother's and baby's blood at some point in the pregnancy. So, when a mother is Rh-negative, and the baby is Rh-positive, then there is a chance of some complication in the subsequent pregnancies if not in the same pregnancy.

What Is Rh Incompatibility?

When two different types of blood get mixed, out of which one is Rh-positive, and the other one is Rh-negative, then it is called Rh incompatibility. Rh incompatibility is also known by the name erythroblastosis fetalis, or Rh induced hemolytic disease of the newborn.

This is an important factor to consider during a blood transfusion. In the context of pregnancy, when the mother's blood group is Rh negative, and the fetus (baby growing in the womb) is Rh positive, then there is a chance of mixing of their blood during pregnancy or at the time of delivery which can lead to some serious complications.

How Does Rh Incompatibility Affect Pregnancy?

Rh factor does not produce any complications in general. However, during pregnancy, it is of significance owing to its risk of serious complications.

When the Rh-positive protein of the developing fetus and the Rh-negative protein of the mother come in contact, the Rh-positive protein is mistaken to be a foreign material by the mother's immune system. As a result of this immune reaction, antibodies are produced against this Rh-positive protein that can cross the placental barrier to reach the fetus and attack the red blood cells of the baby in the womb.

What Are the Possible Situations When Rh Incompatibility Can Occur?

Not every time, there is a mixing of blood between the fetus and mother. However, it can occur in the following situations that could result in Rh incompatibility:

How Is Rh Incompatibility Manifested?

Hemolytic diseases occur when the fetus's red blood cells are destroyed by the antibodies produced by the mother's immune response. Consequently, bilirubin, a breakdown product of the red blood cells, gets accumulated in the body, which might result in the following symptoms after the baby is born:

When Is the Baby at Risk for Rh Incompatibility?

The Rh factor that the baby gets is dependent on the Rh factor of both the mother and father.

The following are the probabilities of getting a positive or negative Rh factor:

The probabilities of getting a positive or negative Rh factor:

How Is the Diagnosis for Rh Incompatibility Made?

Initially, the blood group identification test is taken in the first trimester, along with the routine blood tests. Only in cases when there is vaginal bleeding identifying the blood group at an earlier stage is needed.

If the mother is found to be Rh-negative, then antibody screening for Rh antibodies is done. When the antibody test turns positive, it indicates the fetus is Rh-positive, and there can be chances for Rh incompatibility complications.

On the other hand, if the antibody test is negative, Rh immunoglobulins are injected to prevent antibody formation.

What Pregnancy Complications Arise Due to Rh Incompatibility?

Most of the complications happen during the second pregnancy, and the first pregnancy is spared from this. This is because, during the first pregnancy, there are not enough antibodies that can harm your baby, while the level of antibodies rises considerably when you are pregnant for the second time, which can bring about the below complications.

  1. Abortion.

  2. Intrauterine death of the fetus.

  3. Anemia in the mother.

  4. Severe jaundice in the newborn.

  5. Damaged liver and brain due to intrauterine anemia.

  6. Kernicterus - Brain damage caused by increased levels of bilirubin.

  7. Ascites.

  8. Generalized edema of the fetus (hydrops fetalis).

  9. Low birth weight of the baby.

  10. Compromised mental development of the baby.

  11. Difficulty with movement, speech, and hearing.

  12. Seizures.

How Can We Prevent the Complications of Rh Incompatibility?

The complications arising from Rh incompatibility can be avoided by the following:

When Are Anti-D (RhoGAM) Injections Given for Rh Incompatibility?

  1. When the mother is Rh-negative, and the father is Rh-positive, or if the type of blood group is unknown, the anti-D injection is given in the second trimester.

  2. These injections should be given for each pregnancy regardless of whether the previous pregnancy had complications of Rh incompatibility or not.

  3. It should be taken after a miscarriage or abortion.

  4. The anti-D injections should be taken following a trauma to the abdomen during pregnancy.

  5. Even after taking prenatal tests like amniocentesis or chorionic villus biopsy, these injections should be taken.

  6. In cases where the born child is Rh-positive, the second dose of anti-D injection should be taken after a few days post-delivery.

What Is the Prognosis With Rh Incompatibility?

Once sensitization (mixing) occurs in the mother or when one pregnancy is affected, the prognosis will worsen as the number of pregnancies increases.

What Precautions Should Be Taken to Minimize Complications During Pregnancy in General?

Conclusion:

Rh incompatibility can bring about severe complications in the developing fetus. Therefore, a prompt address of the condition is needed. Taking an anti-D injection is recommended in Rh-negative mothers to prevent the antibody formation that can cause Rh incompatibility. If you are Rh-negative, it is important to inform your doctor about any previous abortions or pregnancies so that they can detect the chances for Rh incompatibility and take necessary preventive measures to avoid complications associated with Rh incompatibility.

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Last reviewed at:
23 Mar 2022  -  5 min read

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