Infant Diet Is Associated With BMI Later in Childhood: A Nation-Wide Mother-Child Cohort Study in Iceland (ICE-MCH).

Few studies have explored associations between indexes incorporating both breastfeeding and complementary feeding and future risk of overweight/obesity. The aim of this study was to explore associations between a previously developed Infant Diet Score (IDS; higher score reflecting better alignment with breastfeeding and complementary feeding guidelines in the first year of life), and the risk of overweight and/or obesity in childhood. Nutrition and anthropometric data for all children born in Iceland in January 2009 to June 2015 were gathered from national health records. Logistic regression models were used to test associations between IDS and BMI-for-age z-scores (WHO standards). Among children for which the IDS could be calculated, anthropometric data was available for 6,335 children at 2.5 years (thereof 7% with overweight/obesity), 2,486 at 4 years (4% with overweight/obesity), 8,946 at 6 years (19% with overweight and 8% obesity) and 5,626 at 9 years (23% with overweight and 15% obesity). Compared to children in the highest IDS quintile, those in quintiles 1 and 2 had higher odds of obesity at 6 years (aOR: 1.42; 95% CI: 1.05-1.93 and aOR: 1.58; 95% CI: 1.18-2.14) and 9 years (aOR: 1.37; 95% CI: 1.02-1.85 and aOR: 1.46; 95% CI: 1.10-1.94). The same applied for IDS quintile 3 in partly, but not fully adjusted models. Associations were inconsistent at 2.5 years and not observed at 4 years. In this national cohort, lower alignment with infant nutrition guidelines was associated with higher risk of obesity at school age.