Head growth evaluation in early childhood, from the Japan Children's Study.

Background:  Head circumference (HC) trajectories are held to reflect neurological development and the acquirement of intelligence. It is important to assess HC growth accurately because atypical HC growth is an indicator of various developmental disorders. HC growth is determined by both familial and physical factors but, hitherto, no one has considered both factors together. The aim of the present study was thus to investigate the relationship between HC, physical growth, and parental HC. Methods:  The study group in the Japan Children's Study consisted of 192 healthy full-term Japanese children. HC (maximum occiptofrontal circumference), height and bodyweight were measured at the ages of 4, 9 and 18 months. Multiple regression analysis were conducted predicting the HC from the body measurements and mid-parental HC (defined as the average of standardized paternal and maternal HC). Results:  Adjusted multiple R2 were 0.336, 0.307 and 0.259, measured at the aforementioned three stages. Bodyweight and mid-parental HC predicted the HC on each occasion (P < 0.01). Bodyweight was more relevant than mid-parental HC. Conclusions:  HC growth is influenced by physical growth and parental HC; therefore, it is important to consider both physical and familial factors. A formula is herein proposed to assess HC using bodyweight and mid-parental HC.