Rh incompatibility occurs when mother and foetus

Options

A. Both are Rh+ve
B. Both are Rh-ve
C. Mother is Rh+ve and foetus is Rh-ve
D. Mother is Rh -ve and foetus is Rh +ve

Answer

**Step-by-Step Solution:**

1. **Understanding Rh Factor:**
- The Rh factor is a protein that can be present on the surface of red blood cells. Individuals can be Rh positive (having the protein) or Rh negative (lacking the protein).

2. **Identifying the Problem:**
- The question asks about Rh incompatibility, which occurs when there is a mismatch between the Rh status of the mother and the fetus.

3. **Analyzing the Options:**
- Option A: Both are Rh positive.
- If both the mother and fetus are Rh positive, there is no incompatibility.
- Option B: Both are Rh negative.
- If both are Rh negative, there is also no incompatibility.
- Option C: Mother is Rh positive and fetus is Rh negative.
- In this case, the mother’s positive status does not harm the fetus, as the mother’s blood will not produce antibodies against the fetus.
- Option D: Mother is Rh negative and fetus is Rh positive.
- This is the critical scenario for Rh incompatibility. When the mother is Rh negative and the fetus is Rh positive, the mother’s immune system may recognize the Rh positive cells as foreign and produce antibodies against them.

4. **Conclusion:**
- The correct answer is Option D: "Mother is Rh negative and fetus is Rh positive." This situation can lead to hemolysis of fetal red blood cells and potential harm to the fetus.