Green space and child weight status : does outcome measurement matter? : evidence from an Australian longitudinal study

Objective: To examine whether neighbourhood green space is beneficially associated with (i) waist circumference (WC) and (ii) waist-to-height ratio (WtHR) across childhood. Methods: Gender-stratified multilevel linear regressions were used to examine associations between green space and objective measures of weight status in the Longitudinal Study of Australian Children, a nationally representative source of data on 4,423 children aged 6 y to 13 y. WC and WtHR were measured objectively. Percentage green space within the local area of residence was calculated. Effect modification by age was explored, adjusting for socioeconomic confounding. Results: Compared to peers with 0-5% green space locally, boys and girls with >40% green space tended to have lower WC (βboys -1.15, 95% CI -2.44, 0.14; βgirls -0.21, 95% CI -1.47, 1.05) and WtHR (βboys -0.82, 95% CI -1.65, 0.01; βgirls -0.32, 95% CI -1.13, 0.49). Associations among boys were contingent upon age (p values age green space<0.001) and robust to adjustment for socioeconomic variables. The benefits of greener neighbourhoods appeared from age 7, with mean WC and WtHR for boys aged 13 y with >40% green space at 73.85 cm and 45.75% compared to those with 0-5% green space at 75.18 cm and 46.62%, respectively. Conclusions: Greener neighbourhoods appear beneficial to alternative child weight status measures, particularly among boys.