Blood Group (Rhesus) Incompatibility: What is it and how does it affect the Newborn?

Rhesus incompatibility, also known as Rh incompatibility, is a condition that occurs during pregnancy when a mother and her unborn baby have different Rhesus (Rh) blood group factors. Specifically, this situation arises when an Rh-negative mother carries an Rh-positive fetus. The incompatibility can lead to complications if not managed properly, making it a significant concern in obstetrics.

Understanding Rhesus Factor

The Rhesus factor is a protein found on the surface of red blood cells. People who have this protein are considered Rh-positive, while those who lack it are Rh-negative. The presence or absence of this factor is genetically determined. Approximately 85% of people are Rh-positive, while the remaining 15% are Rh-negative.

Rhesus incompatibility primarily becomes a concern during pregnancy. If an Rh-negative woman conceives a child with an Rh-positive man, there is a possibility that the unborn baby will inherit the Rh-positive factor from the father. During pregnancy or delivery, the baby’s Rh-positive blood cells can enter the mother’s bloodstream. The mother’s immune system may recognize these cells as foreign and produce antibodies against them. This process is known as sensitization.

Once sensitization occurs, any future pregnancies with an Rh-positive baby are at risk. The antibodies produced by the Rh-negative mother can cross the placenta and attack the red blood cells of the Rh-positive unborn baby. This attack can lead to haemolytic disease of the newborn (HDN), in which the baby’s red blood cells break down fast, causing severe anemia, jaundice, heart failure, and even death if not properly managed.

Prevention and Treatment

Prevention of Rh incompatibility is primarily achieved through the administration of Rh immunoglobulin (RhIg), commonly known as Rho(D) immune globulin (RhoGAM). This preventive treatment is given to Rh-negative mothers during pregnancy and after delivery if the baby is Rh-positive. RhIg works by preventing the mother’s immune system from recognizing and attacking Rh-positive cells.

Specific Strategies Include:

Prenatal Care: Early prenatal care involves blood type and Rh factor testing for all pregnant women. If the mother is Rh-negative, the father's Rh status may also be tested to assess the risk of incompatibility.
Rh Immunoglobulin Administration: Rh-negative mothers typically receive RhIg at around 28 weeks of pregnancy and within 72 hours after the birth of an Rh-positive baby. It is also given after any event where fetal cells might mix with the mother’s blood, such as amniocentesis, miscarriage, or trauma.
Monitoring: In sensitized pregnancies, where the mother has already developed antibodies, close monitoring of the fetus is essential. This includes regular ultrasounds and Doppler studies to assess fetal anemia. In severe cases, intrauterine transfusions may be necessary to treat the fetus.

Case Management and Complications

Proper management of Rh incompatibility involves a multidisciplinary approach. Obstetricians, pediatricians, and hematologists work together to monitor and treat both the mother and the baby. Complications from untreated Rh incompatibility can be severe, but with appropriate prevention and intervention, the outcomes can be significantly improved.

In conclusion

Rhesus incompatibility is a potentially serious condition that can have significant implications for both the mother and the baby. Understanding the mechanisms, preventive measures, and management strategies is crucial for healthcare providers to ensure positive pregnancy outcomes. Advances in prenatal care and preventive immune medicine have greatly reduced the incidence of complications associated with Rh incompatibility, making it a manageable condition with timely intervention.