Impaired head circumference growth and behavioural problems in childhood: Longitudinal findings from the MINA-Brazil birth cohort.

Background: Previous evidence on the relation between early head circumference (HC) growth and behavioural outcomes in preschoolers has been inconsistent.

Objective: We aimed to investigate whether HC growth from birth to 5 years of age was related to internalising or externalising behavioural problems at 5 years of age in a sex-specific manner.

Methods: Among 303 girls and 318 boys from the MINA-Brazil birth cohort, we examined the associations between changes in HC from birth to 5 years of age and internalising and externalising behaviour problem scores at 5 years according to the Strengths and Difficulties Questionnaire for parents. HC values were transformed into sex- and age-specific z-scores (HCZ) using World Health Organisation standards, and the differences between values at 5 years of age and birth were classified into quintiles. We estimated adjusted mean differences with 95% confidence intervals in behavioural problem scores between HCZ change quintiles using multivariable linear regression by sex. To examine nonlinear associations, we included cubic spline terms.

Results: Head circumference growth from birth to 5 years of age was inversely and nonlinearly associated with internalising problems in girls. Compared with girls at the lowest quintile of HC growth, those above had an adjusted 1.27 (95% confidence interval 0.28, 2.27) points lower mean internalising problems score. This association was mostly driven by HC growth during the first 2 years. We found no association between HC growth and externalising behaviour in either sex.

Conclusions: Impaired HC growth was related to higher mean internalising problem scores at 5 years of age in girls but not in boys. HC growth was not associated with externalising problems.