This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intra Uterine Growth Restriction, Intrapaum and Antepaum Fetal Surviellance, Subject name: Gynaecology & Obstetrics
Best fetal parameter to diagnose IUGR fetus is:- 
Select and explain. 
A. Femur length, B. Head circumference, C. Abdominal circumference, D. CRL
C: Abdominal circumference
Answer: C: Abdominal circumference 
Explanation: Estimation of IUGR is frequently made by the ratio of Head to abdominal circumference HC/AC ratio.This ratio compares the most preserved organ in the malnourished fetus, the brain, represented by the circumference of the fetal head, with the most compromised organ, the liver, represented by the fetal AC. Head circumference is last to be affected. Since the liver is first organ be affected in IUGR babies, the abdominal circumference will be first parameter to be compromised in growth restriction