Abstract 

Background: Attending government-regulated centre-based childcare may influence important health behaviours including dietary quality, physical activity and routines related to child growth. However, the relationship between centre-based childcare and childhood obesity remains unclear.

Objectives: The primary objective was to evaluate the association between centre-based childcare attendance in early childhood and body mass index z-score (zBMI) in later childhood. Secondary objectives included exploring whether family income, child sex, or non-centre-based setting modified these relationships.

Methods: A prospective cohort study of children aged 1 to 10 years who participated in the TARGet Kids! cohort was conducted. Linear mixed-effect modelling was used to evaluate the relationship between centre-based childcare attendance (in hours/week) compared to non-centre-based childcare between 1-4 years of age and zBMI between 4 and 10 years of age. Generalised estimating equation modelling was used to explore weight status categories. Models were adjusted for confounders and effect modification was explored.

Results: A total of 3503 children were included. Children who attended centre-based childcare full-time (40 h/week) had 0.11 (95% CI: -0.19, -0.03; p = 0.01) lower zBMI at 4 and 7 years of age and lower odds of overweight and obesity at 4 years (OR 0.78; 95% CI: 0.62, 0.97; p = 0.03), but no evidence of an association was found at 10 years of age. Children from families with income < $50,000CDN who attended centre-based childcare full-time had 0.32 (95% CI: -0.50, -0.14; p = 0.001) lower zBMI and lower odds of overweight and obesity (OR 0.52; 95% CI: 0.28, 0.99; p = 0.05) at 10 years of age.

Conclusions: Attending centre-based childcare in early childhood was associated with a lower zBMI and odds of overweight and obesity in later childhood. These associations were stronger for children from lower income families. Centre-based childcare may be an early intervention for the prevention of childhood obesity.