A head circumference that is less than 2 standard deviations from the mean suggests possible stunting, but if it is not less than 2 standard deviations, it may be normal. Measurement of head circumference is most valuable up to 2 years of age. The average head circumference of infants is 33-34 cm at birth, and during the first year, the increase in head circumference in the first three months is approximately equal to the increase in head circumference in the second nine months. The head circumference of infants is approximately 48 cm at age 2 years, and increases only 6-7 cm between the ages of 2 and 15 years. Continuous tracking and multiple measurements of head circumference during infancy and childhood are more valuable than just one measurement of head circumference. If the head circumference is small for its age, within 2 standard deviations, it is usually normal. If the head circumference is smaller than that of the same age group, a difference of more than 2 standard deviations is often indicative of brain dysplasia; if the difference is more than 3 standard deviations or more, it is indicative of brain dysplasia and requires further diagnosis and treatment. If you feel unwell, please consult a doctor.