Objectively measured waist circumference is most strongly associated in father–boy and mother–girl dyads in a large nationally representative sample of New Zealanders

Background: The prevalence of children with elevated weight or obesity is concerning for public health due to associated comorbidities. This study investigates associations between parental adiposity, physical activity (PA), fruit and vegetable consumption, and child adiposity and moderation by both child and parent gender. Methods: Cross-sectional nationally representative data from the New Zealand Health Survey were pooled for the years 2013/14–2016/17. Parent and child surveys were matched resulting in 13,039 child (2–14 years) and parent (15–70 years) dyads. Parent and child, height (cm), weight (kg) and waist circumference (WC) were measured objectively. Height and weight were used to calculate BMI. Linear regression, accounting for clustered samples (b [95% CI]) investigated associations between parental characteristics and child BMI z-score and WC. Interactions and stratification were used to investigate effect moderation by parent gender, child gender, and parent adiposity. Results: Parental PA and fruit and vegetable consumption were unrelated to child adiposity. Overall, higher parent BMI was related to a higher child BMI z-score (b = 0.047 [0.042, 0.052]) and higher parental WC was related to a higher child WC (0.15 [0.12, 0.17]). A three-way interaction revealed no moderation by parent gender, child gender, and parent BMI for child BMI z-score ((b = 0.005 [−0.017, 0.027], p = 0.318). However, a three-way interaction revealed moderation by parent gender, child gender, and parent WC for child WC (b = 0.13 [0.05, 0.22]). The slightly stronger associations were seen between father–son WC (b = 0.20 [0.15, 0.24]) and mother–daughter WC (b = 0.19 [0.15, 0.22]). Conclusions: The findings are highly relevant for those wishing to understand the complex relationships between child-parent obesity factors. Findings suggest that family environments should be a key target for obesity intervention efforts and show how future public health interventions should be differentiated to account for both maternal and paternal influences on child adiposity. © 2020, The Author(s), under exclusive licence to Springer Nature Limited.