A full-term neonate has a head circumference of 35 cm at birth. The infant is exclusively breastfed and growing appropriately. What is the expected head circumference at 1 year of age, assuming normal growth velocity?
- A 43 cm
- B 45 cm
- C 47 cm ✓
- D 49 cm
Correct answer: C. 47 cm
Explanation
Head circumference increases by approximately 1 cm per month for the first 6 months, then by about 0.5 cm per month from 6 to 12 months. Birth HC of 35 cm plus 6 cm (first 6 months) plus 3 cm (next 6 months) equals approximately 44 cm, but the average term birth HC is 35 cm and 1-year HC averages 47 cm. The brain doubles its size by 12 months. Microcephaly is defined as HC more than 2 standard deviations below the mean for age and sex.
Reference: Nelson Textbook of Pediatrics, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.