All about the rhesus factor blood system and compatibility chart for marriage

The rhesus (Rh) factor is an important component of the blood system. Studying your blood type along with the rhesus factor compatibility chart will help prevent pregnancy and childbirth complications.

A pregnant woman with a doctor explaining the rhesus factor compatibility chart for her in the consultation room

Aside from the ABO blood group system, the rhesus (Rh) system is another important blood group system that should be considered in marriages. This is because it can affect your biological children

The ABO blood group system divides blood groups into 4 types - A, B, AB, and O. However, the Rh factor further divides the ABO blood types into 8, depending on the presence or absence of another antigen called the RhD antigen. 

Everybody either has the RhD present or absent in their blood. If you have it, your blood group is RhD-positive; if absent, it is RhD-negative. The rhesus factor in blood grouping is represented in the following ways:

  • Blood group A+
  • Blood group A-
  • Blood group B+
  • Blood group B-
  • Blood group AB+
  • Blood group AB-
  • Blood group O+
  • Blood group O-

Many people have the RhD antigen present in their blood. About 83% of people in the United Kingdom are RhD positive.

Another study of the prevalence of RhD-negative among reproductive-age women in Southern Ethiopia showed that only 1%, 1.2%, 1.9%, and 2.1% of participants with blood groups AB, B, A, and O, respectively, were RhD-negative.

However, this doesn’t mean that people who are RhD negative are sick or have disorders. In fact, O- blood is considered safe for transfusing to all blood groups and is often used in emergency situations when the patient’s blood type is not yet known.

How rhesus factor can affect marriage and babies

The rhesus factor in blood group types can affect some marriages, particularly for couples who want to have their own biological children. This is because it can cause serious complications in children which can put a strain on the marriage.

The rhesus factor may become an issue when a mother is Rh- and their spouse is Rh+. In such a case, there are chances that they could give birth to a child with either Rh+ or Rh-negative blood type.

If a child is born to an Rh-negative mother and an Rh-positive father is Rh-negative, it won’t cause a problem because the mother and child don’t have the RhD antigen. 

But if the child inherits the antigen from the father and is RhD+, this becomes a problem because red blood cells from the Rh-positive baby can cross over to the mother’s Rh-negative bloodstream, triggering an immune system response.

The mother’s immune system may build antibodies to attack the RhD+ antigen from the baby. 

The antibodies formed may also cross back into the baby’s blood from the placenta, where they will destroy the baby’s red blood cells. This can cause the yellowing of the eyes and skin in babies (jaundice) and lethargy. The effects of this on the baby can range from mild to severe.

Rhesus (Rh) compatibility chart

Here is a rhesus blood compatibility table that shows rhesus factor compatibility for marriage. The table shows different rhesus factor statuses and when they can cause an increased risk of complications in babies.

The rhesus factor compatibility chart is similar to the blood group compatibility chart. However, while the blood group compatibility chart only shows compatible and incompatible blood groups for blood transfusion, the rhesus factor compatibility chart shows when parents' rhesus factor components can cause complications in their biological babies.

When Rh antibodies cause complications

Just like ABO blood grouping, the rhesus factor system will not determine whether a couple will have a great marital relationship or not. But, it can cause issues with childbirth and child nursing, which can ultimately put a strain on the marriage. 

Rh factor incompatibility often does not cause problems when the mother is RhD+, and the father is RhD-. This is because when the mother is Rh-positive, her system cannot make anti-Rh antibodies to attack the baby. Problems also don’t arise when both mother and child are Rh-negative.

But when a mother is Rh- and the baby is Rh+, the mother’s immune system forms antibodies to attack antigens on the baby’s red blood cells. 

First-born babies are often not affected unless the mother had an abortion or miscarriage earlier, which caused her immune system to develop antibodies against the RhD antigen. The next time she gets pregnant with an Rh+ baby, her antibodies will attack the baby’s blood cells when they come in contact. This usually happens during childbirth.

Destruction of the baby's red blood cells can lead to hemolytic anemia which occurs when the red blood cells are destroyed faster than they can be replaced. Severe cases of hemolytic anemia can lead to liver failure, jaundice, and heart failure.

Other complications that can be caused by Rhesus factor incompatibility include:

  • Fluid build-up (swelling) in baby
  • Mental problems
  • Brain damage caused by a high level of bilirubin accumulation
  • Problems with hearing and movement

While babies are affected, mothers are usually not affected. Doctors often treat complications quickly. Depending on the severity, your child may receive blood transfusions or may be treated using special lights to reduce bilirubin levels.

Your doctor will discuss other effective treatment methods with you.

How to prevent Rh incompatibility complications

To avoid complications that may arise due to rhesus factor incompatibility, Rh-negative mothers should seek medical attention from their gynecologist when pregnant. 

Fortunately, special immune globulin, also called Rh Immunoglobin (RhIg) or RhoGAM, is now used to treat this blood incompatibility issue.

RhoGAM is a medicine that stops a mother’s Rh-negative blood type from making anti-RhD antibodies that attack their baby’s Rh+ blood cells. RhoGAM is often given as a shot, usually at 28 weeks of pregnancy and within 72 hours of delivering a baby with RhD-positive blood.

Aside from during pregnancies, women with Rh-negative blood may also need to get RhoGAM injections:

  • After an abortion
  • After a miscarriage
  • After they have an injury in the abdomen during pregnancy
  • After running some pregnancy tests such as chorionic villus biopsy

Why you should understand Rh compatibility

Learning about the rhesus system and the rhesus factor compatibility chart will help couples understand how their blood types can affect their biological children.

It also helps women with Rh-negative blood types prepare on time for having babies by seeing their doctors and taking medications to prevent their immune system from attacking their babies’ red blood cells.

This will reduce stress for many families and prevent them from spending much on medical treatments for their babies.

Summary

The rhesus factor is an important component of the blood system. It is not a disease condition; however, it can affect Rh-positive babies conceived by Rh-negative mothers.

If you don’t know your rhesus factor status, you may want to take a blood typing test. While the rhesus factor doesn’t stop many couples from getting married, it will help to know your status on time so that you can prepare for childbirth.

Fortunately, RhoGAM is an effective medication for preventing a mother’s blood from attacking their baby’s blood. So, if you find out you are Rh-negative, you should see a gynecologist when you get pregnant to get the needed preventive care.

References

  1. American College of Obstetricians and Gynecologists. (2020). The Rh factor: How it can affect your pregnancy
  2. American Red Cross. (n.d.). What is the Rh factor? Why is it important?
  3. Kanko, Tesfaye K, and Melat K Woldemariam. (2021). Prevalence of Rhesus D negativity among reproductive-age women in Southern Ethiopia: a cross-sectional study.
  4. MedlinePlus. (2020). Rh incompatibility.
  5. National Health Service. (2020). Blood groups.