What Every Parent Should Know About Rh Incompatibility in Pregnancy

Understanding Rh incompatibility is critical to protecting the health of the mother and unborn baby. It is essential for expecting parents to discuss Rh incompatibility, including its causes, risks and management strategies, with their healthcare provider.  

What is the Rh factor? Why is it important?

Rh factor stands for Rhesus factor. It refers to the protein present in red blood cells. The majority of people carry this protein, and they are known as Rh-positive. Certain people who do not carry Rh protein are called Rh-negative.  

Rh factor is important for several reasons  

• Pregnancy: If a Rh-negative mother is carrying a Rh-positive baby, it can lead to Rh incompatibility. This can cause the mother’s immune system to produce antibodies against the baby’s red blood cells, potentially leading to haemolytic disease in newborns.
• Blood transfusions: The importance of the Rh factor is significant during blood donations and blood transfusions. An individual possessing Rh positive factor will not generate Rh antibodies. Conversely, individuals with Rh-negative factor will synthesise these antibodies. Consequently, an individual with Rh-positive blood can receive transfusions from both Rh-positive and Rh-negative blood groups, whereas an individual with Rh-negative blood can solely accept transfusion from Rh-negative blood. The examination of blood type and Rh factor is conducted not only for the purpose of classifying blood donations, as the results of the Rh screening test enable healthcare providers to offer enhanced support to patients in cases where incompatibility is identified.
• Medical procedure: When the healthcare provider knows about your Rh incompatibility, precautions are taken to prevent adverse effects.

Understanding the role of the Rh factor in pregnancy

The Rh factor plays a critical role in pregnancy, especially when there is an Rh incompatibility between the mother and the foetus. Here’s how it works:

• Rh incompatibility: This happens when a Rh-negative mother is carrying an Rh-positive baby. The mother’s immune system may recognise the infant’s Rh-positive red blood cells as foreign substances and produce antibodies against them.
• Sensitisation: A small amount of the baby’s blood may get mixed with the mother’s blood during the pregnancy, at the time of delivery or during medical procedures. If the mother is Rh-negative and the baby is Rh-positive, the mother’s immune system can become sensitised and start producing antibodies.
• Impact on the baby: These antibodies can move across the placenta and attack the baby’s red blood cells, resulting in haemolytic disease of the newborn (HDN). This can cause severe anaemia, jaundice and other health issues in the baby.

Symptoms of Rh Incompatibility

Rh incompatibility can lead to a range of symptoms, from mild to severe. In its mildest form, it causes the destruction of red blood cells without other effects. After birth, affected infants may exhibit:

• Jaundice: The colour of the whites of the eyes and skin changing to yellow
• Hypotonia and lethargy: Low muscle tone and general lethargy

Rh factor test

The United States Preventive Task Force highly recommends that all pregnant women undergo Rh(D) blood type and antibody screening during their initial prenatal visit. Additionally, for Rh-negative mothers who have not developed, the committee recommends repeat antibody testing between 24 and 28 weeks of pregnancy unless the father is also Rh-negative. Antibody testing should be conducted at the time of delivery. There are many outcomes after initial testing:

• If a mother is Rh-positive, there is no risk of her body reacting to the baby’s blood type, no matter what the baby’s Rh type is.
• If the mother is Rh-negative, doctors will check for antibodies in her blood to see if her body is reacting to the baby’s blood.
• If the Rh-negative mother has antibodies, a comb test is conducted to confirm and guide further care during pregnancy.
• If the mother doesn’t have antibodies, the father’s Rh type can be tested to help with planning and monitoring.

When to get tested for the Rh factor?

If you are Rh-negative, your partner may also be tested. If your partner is Rh-negative, too, there’s no risk of Rh incompatibility. However, if your partner is Rh-positive and you are Rh-negative, your doctor will check for signs of Rh incompatibility, such as:

• Positive indirect Coombs test: This blood test looks for antibodies in your blood that could attack the baby’s red blood cells.
• High bilirubin levels in the baby: In a full-term baby less than 24 hours old, bilirubin levels should be below 6.0 milligrams per decilitre. Higher levels can indicate Rh incompatibility.
• Red blood cell destruction: The shape and structure of the baby’s red blood cells can show signs of being destroyed, which can be seen under a microscope.
• Maternal antibodies in baby’s blood: Your doctor can test the baby’s blood for antibodies from the mother that are breaking down the baby’s red blood cells.

Treatment

Treatment for affected infants with Rh incompatibility depends on the severity of the condition:

• Mild cases: Phototherapy using bilirubin lights and possibly intravenous immune globulin (IVIG)
• Severe cases: Exchange transfusion of blood to reduce bilirubin levels
• Prognosis: Infants with mild Rh incompatibility typically make a full recovery. However, complications can arise, including:
• Kernicterus: Brain damage due to high bilirubin levels
• Hydrops fetalis: Fluid buildup and swelling in the baby
• Long-term issues: Problems with mental function, movement, hearing, speech and seizures

Prevention

Rh incompatibility is almost entirely preventable. Rh-negative mothers should be closely monitored during pregnancy. Special immune globulins, such as RhoGAM, are used to prevent Rh incompatibility. If the father is Rh-positive or his blood type is unknown, the mother receives a RhoGAM injection during the second trimester. This injection is administered to prevent the emergence of antibodies against Rh-positive blood. If the baby is Rh-positive, the mother gets a second injection within a few days post-delivery. Rh-negative women need these injections:

• During every pregnancy
• After a miscarriage or abortion
• Following prenatal tests like amniocentesis and chorionic villus sampling
• After any abdominal injury during pregnancy

Conclusion

If you are pregnant but unsure of your Rh status, you need to start with routine prenatal care, where blood-type testing will be done. Early diagnosis and treatment of Rh incompatibility can allow you to focus on what matters most is welcoming a healthy new baby.