"Microsomia" is defined as:
b. Birth weight below 10th percentile(Ref: Nelson's 20/e p 789-791, Ghai 8/e p 124-125)Microsomia is another name for a small for date (SFD) or small for gestational age (SGA) baby.SFD baby is a baby whose birth weight is less than 10th centile of expected according to the gestational age.
Birth weight below 90th percentile
Birth weight below 10th percentile
Birth weight below 20th percentile
Birth weight below 5th percentile
Newborn Infant - Physical Examination