Question

When does haemolytic disease of newborn happen in case of Rh blood group system?
• Rh blood group system of husband and wife are incompatible.
• Rh blood group system of father and newborn are incompatible.
• Rh blood group system of mother and newborn are compatible.
• Rh blood group system of husband and wife are compatible.

• A. \(1\)
• B. \(2\)
• C. \(3\)
• D. \(4\)

Hint:

Remember the classic HDN condition: \[ \text{Mother } Rh^- \quad \text{and Father } Rh^+ \] This may produce an \(Rh^+\) baby, leading to antibody formation and destruction of fetal RBCs in later pregnancies.

Answer 1

The Correct Option is A

Concept:
Haemolytic Disease of the Newborn (HDN), also called: \[ Erythroblastosis fetalis \] is a medical condition that occurs due to incompatibility between the blood groups of the mother and the fetus, especially involving the: \[ Rh factor \] The Rh factor is an antigen present on red blood cells:
• If present \(\rightarrow\) Rh positive (\(Rh^+\))
• If absent \(\rightarrow\) Rh negative (\(Rh^-\)) The disease usually develops when: \[ \text{Mother is } Rh^- \quad \text{and fetus is } Rh^+ \] This incompatibility generally arises because: \[ \text{Father is } Rh^+ \]

Step 1: Understanding Rh incompatibility between husband and wife.
Suppose: \[ \text{Mother} = Rh^- \] and \[ \text{Father} = Rh^+ \] Then the baby may inherit: \[ Rh^+ \] from the father. During pregnancy or childbirth, fetal blood cells may enter the mother's bloodstream. The mother's immune system recognizes the Rh-positive cells as foreign and produces: \[ \text{Anti-Rh antibodies} \] In subsequent pregnancies, these antibodies can cross the placenta and destroy fetal red blood cells. This destruction causes:
• Anaemia
• Jaundice
• Organ enlargement
• Severe fetal complications Thus, haemolytic disease develops because of Rh incompatibility between parents.

Step 2: Analyzing Option (1).
\[ \text{Rh blood group system of husband and wife are incompatible} \] This statement correctly explains the condition responsible for Rh incompatibility and HDN. Therefore: \[ \boxed{\text{Option (1) is correct}} \]

Step 3: Analyzing Option (2).
\[ \text{Rh blood group system of father and newborn are incompatible} \] This is not the main clinical reason for HDN. The disease depends primarily on incompatibility between: \[ \text{Mother and fetus} \] Hence this option is incorrect.

Step 4: Analyzing Option (3).
\[ \text{Rh blood group system of mother and newborn are compatible} \] If both are compatible, antibodies are not produced and HDN does not occur. Hence this statement is incorrect.

Step 5: Analyzing Option (4).
\[ \text{Rh blood group system of husband and wife are compatible} \] Compatibility prevents the disease. Therefore, this option is incorrect.

Step 6: Final conclusion.
Haemolytic disease of the newborn occurs due to: \[ \boxed{\text{Rh incompatibility between husband and wife}} \] Hence, the correct answer is: \[ \boxed{(1)} \]