A 20yr old P1L1 with RhD negative pregnancy had a spontaneous vaginal delivery. Her baby is RhD positive. Anti D Ig should be administered within

**Core Concept**
The underlying principle being tested is the prevention of RhD alloimmunization in RhD negative mothers who deliver RhD positive babies. This is crucial to prevent hemolytic disease of the newborn in future pregnancies.

**Why the Correct Answer is Right**
Anti-D Ig administration is necessary to prevent the formation of anti-RhD antibodies in the mother. The correct timeframe for administration is within 72 hours of delivery, as this is when the risk of sensitization is highest.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct timeframe.
**Option B:** This option is incorrect because it is too late for effective prevention of sensitization.
**Option C:** This option is incorrect because it is not the standard recommended timeframe.
**Option D:** This option is incorrect because it is not provided.

**Clinical Pearl / High-Yield Fact**
It is essential to administer Anti-D Ig within 72 hours of delivery to prevent RhD alloimmunization.

**Correct Answer:** C. 72 hours of delivery

✓ Correct Answer: A. 72 hours