Adherence to national infant feeding guidelines is associated with child overweight/obesity and central obesity at age 54- months: results from the Growing up in New Zealand cohort study

Abstract

Purpose: Despite evidence that childhood obesity is influenced by early life events and environmental exposures, the contribution of diet in infancy to the development of overweight/obesity remains relatively unexplored. Most studies investigating the effect of infant feeding on overweight/obesity focus on discrete practices (e.g. breastfeeding) and do not consider dietary quality more broadly. We examined associations between adherence to the New Zealand (NZ) national infant feeding guidelines and development of child overweight/obesity and central obesity at age 54-months. Methods: Data were collected on 6,435 infants born in 2009-10, enrolled during pregnancy into the Growing Up in NZ cohort study. Adherence to the guidelines was measured by an Infant Feeding Index (IFI) which was created based on the Ministry of Health’s Food and Nutrition Guidelines (2008). The IFI score ranged from 0 (no adherence) to 12 (complete adherence). Anthropometric measurements and screen time were collected at the 54-month interview. Body-mass-index/age (BMI/A) was calculated and classified according to WHO 2006 growth standards (overweight/obesity: >+2z scores). Waist-to-height ratio (WtHR) >90th percentile identified children with the highest values for central obesity. Maternal sociodemographic and health behaviour characteristics were described from the antenatal face-to-face interview. Adjusted Poisson regressions with robust variance (risk ratios-RR and 95% confidence intervals-95%CIs) were applied to examine the effect of the IFI scoring (in tertiles) on BMI/A and WtHR. Models were adjusted for maternal antenatal characteristics, screen time and exact age at the 54-month interview (p<0.05). Results: In the fully adjusted model and compared to children in the highest tertile of the IFI, girls who scored in the lowest and middle tertiles were more likely to have BMI/A>+2z at 54-months (RR=1.46, 95%CI 1.03-2.06 and RR=1.55, 95%CI 1.08-2.21 respectively), and boys who scored in the lowest tertile of the IFI were more likely to have WtHR >p90th at 54-months (RR=1.59, 95%CI 1.06-2.39). Conclusions: In this NZ nationally-generalizable birth cohort, lower adherence to national infant feeding guidelines was associated with the development of overweight/obesity and central obesity in early childhood, with gender differences evident. Improvement in infant feeding practices is a potential strategy for prevention of childhood obesity.