Socioeconomic inequalities in children's weight, height and BMI trajectories in Norway

Studies exploring when social inequalities in body mass index (BMI) and its composites emerge and how these evolve with age are limited. Thus, this study explored parental income and education related inequalities in children's weight, height, weight velocity and body mass index among Norwegian children from 1month to 8years. The study population included 59,927 family/children pairs participating in the Norwegian Mother, Father, and Child Cohort Study. Growth was modelled using the Jenss-Bayley model and linear mixed effects analyses were conducted. Maternal and paternal educational differences in children's weight and BMI trajectories emerged during infancy, continuing to age 8years. Parental income-related inequalities in children's weight were observed from the age of 1month to 4years for maternal and up to 1year for paternal income-related differences but then disappeared. Parental income-related inequalities in child's BMI were observed from 18months to 8years for maternal income, and from 9months to 8years for paternal income-related differences. These results suggest that social inequalities in children's BMI present early in infancy and continue to 8years of age. The inequalities sometimes differed by indicator of socioeconomic position used. Interventions to combat these inequalities early in life are, thus needed.