This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: New born infants, Subject name: Pediatrics
"Microsomia" is defined as 
Select and explain. 
A. Bih weight below 90th percentile, B. Bih weight below 10th percentile, C. Bih weight below 20th percentile, D. Bih weight below 50th percentile
B: Bih weight below 10th percentile
Answer: B: Bih weight below 10th percentile 
Explanation: A neonate whose weight falls between the 10th and <90th percentile for gestational age is considered as Appropriate for gestational age (AGA). If the weight falls below the 10th percentile, the neonate is classified as Small for gestational age (SGA) or microsomic. If the weight falls at or above the 90th percentile, then the neonate is classified as Large for gestational age (LGA) or macrosomic. Reference : page 137 Ghai Essential Pediatrics 8th edition