What would be the blood group of a father who has a child suffering from erythropoiesis foetalis ?

Options

A. Father's blood group is definitely Rh-ve
B. Father's blood group is definitely Rh+be
C. Father's blood group may ne definitely Rh+ve or Rh-ve
D. Father's blood group is definitely O Rh-ve

Answer

To determine the blood group of the father whose child is suffering from erythroblastosis fetalis, we need to understand the underlying immunological mechanism involved in this condition.

### Step-by-Step Solution:

1. **Understanding Erythroblastosis Fetalis**:
- Erythroblastosis fetalis is a condition where the red blood cells (RBCs) of the fetus are destroyed by the antibodies produced by the mother. This typically occurs when there is an incompatibility between the blood types of the mother and the fetus.

2. **Role of Rh Factor**:
- The Rh factor is a protein that can be present on the surface of red blood cells. Individuals who have this protein are classified as Rh positive (Rh+), while those who do not are classified as Rh negative (Rh-).

3. **Parental Blood Types**:
- For erythroblastosis fetalis to occur, the mother must be Rh negative (Rh-) and the father must be Rh positive (Rh+). This is because if the father is Rh positive, the first child can inherit the Rh positive blood type from the father.

4. **First Pregnancy**:
- In the first pregnancy, if the child is Rh positive and the mother is Rh negative, during delivery, some of the fetal blood (which contains Rh antigens) may mix with the mother's blood. This exposure causes the mother to produce antibodies against the Rh factor.

5. **Subsequent Pregnancies**:
- In any subsequent pregnancies, if the next child is also Rh positive, the antibodies produced by the mother during the first pregnancy can cross the placenta and attack the fetal red blood cells, leading to erythroblastosis fetalis.

6. **Conclusion**:
- Therefore, for the child to suffer from erythroblastosis fetalis, the father must be Rh positive. The specific ABO blood group of the father (A, B, AB, or O) is not directly relevant to the condition, but the Rh factor is crucial.

### Final Answer:
The blood group of the father must be Rh positive (Rh+).