Variability in head circumference growth rate during the first 2 years of life

The head circumference (HC) curves were plotted for a group of 415 healthy full-term babies over the first 2 years of life. Two hundred ten (51%) of the cohort demonstrated HC variability, defined as an HC acceleration or deceleration of at least 1 centile curve for at least 2 months. Of these, the deceleration pattern was predominant (80.9%), and also frequently permanent (87%). The HCs of 3 (1.42%) of 210 infants with HC variability ended up with a deviation of 2 standard deviations or more from the mean. The onset of HC transition occurred from the mean age of 1.3 months, and the new curve had stabilized by age 13 months in 95% of the study group. Parallel changes occurred in body weight and body length in approximately 48% of the total cohort, but more frequently in the variable-HC group. The clinical interpretation of these findings is discussed.