An ecological systems approach to examining risk factors for early childhood overweight: findings from the UK Millennium Cohort Study

Objective: To use an ecological systems approach to examine individual-, family-, community- and area-level risk factors for overweight (including obesity) in 3-year-old children. Methods: A prospective nationally representative cohort study conducted in England, Wales, Scotland, Northern Ireland. Participants included 13 188 singleton children aged 3 years in the Millennium Cohort Study, born between 2000 and 2002, who had complete height/weight data. The main outcome measure was childhood overweight (including obesity) defined by the International Obesity TaskForce cut-offs for body mass index. Results: 23.0% of 3-year-old children were overweight or obese. In the fully adjusted model, primarily individual-and family- level factors were associated with early childhood overweight: birthweight z-score (adjusted odds ratio, 1.36, 95% CI 1.30 to 1.42), black ethnicity (1.41, 1.11 to 1.80) (compared with white), introduction to solid foods,4 months (1.12, 1.02 to 1.23), lone motherhood (1.32, 1.15 to 1.51), smoking during pregnancy (1-9 cigarettes daily: 1.34, 1.17 to 1.54; 10-19: 1.49, 1.26 to 1.75; 20+: 1.34, 1.05 to 1.70), parental overweight (both: 1.89, 1.63 to 2.19; father only: 1.45, 1.28 to 1.63; mother only: 1.37, 1.18 to 1.58), prepregnancy overweight (1.28, 1.14 to 1.45) and maternal employment >= 21 hours/week (1.23, 1.10 to 1.37) (compared with never worked). Breastfeeding >= 4 months (0.86, 0.76 to 0.97) (compared with none) and Indian ethnicity (0.63, 0.42 to 0.94) were associated with a decreased risk of early childhood overweight. Children from Wales were also more likely to be overweight than children from England. Conclusions: Most risk factors for early childhood overweight are modifiable or would allow at-risk groups to be identified. Policies and interventions should focus on parents and providing them with an environment to support healthy behaviours for themselves and their children.