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

Abstract

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 1 month to 8 years. 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 8 years. Parental income-related inequalities in children’s weight were observed from the age of 1 month to 4 years for maternal and up to 1 year for paternal income-related differences but then disappeared. Parental income-related inequalities in child’s BMI were observed from 18 months to 8 years for maternal income, and from 9 months to 8 years for paternal income-related differences. These results suggest that social inequalities in children’s BMI present early in infancy and continue to 8 years of age. The inequalities sometimes differed by indicator of socioeconomic position used. Interventions to combat these inequalities early in life are, thus needed.

Mediators of differences by parental education in weight-related outcomes in childhood and adolescence in Norway

“…The use of a growth model helps to handle the missing anthropometric measurements and overcome the loss to follow-up. Given that a high correlation between the measured and predicted anthropometric measurements was documented 16 , the predicted anthropometric measurements were used in this study.…”

“…The anthropometric measurements at birth were obtained from the Medical Birth Registry, while measurements in infancy and up to 8 years were routinely conducted by health professionals at well-child clinics and school health services and registered in a health card from which mothers were asked to report information into MoBa questionnaires. More detail of anthropometric measurements of children from birth to 8 years is described elsewhere 16 . The anthropometric measurements for the 14 years old (average age) were obtained from the youth dietary questionnaire (Q-youth diet) developed to monitor the youths’ food intake at the age of 13–15 years.…”

“…conditional excess weight gain at 2 years, OW/OB at 5 and 8 years) were based on the predicted anthropometric measurement derived using the Jenss–Bayley growth curve model from 1 month to 8 years 49 . The weight and height of the child derived from the growth model from the age of 1 month to 8 years were used to define our outcome variables; details described elsewhere 16 . The use of a growth model helps to handle the missing anthropometric measurements and overcome the loss to follow-up.…”

“…High rates of OW/OB 7 , 22 , 23 and SEP inequalities in BMI or OW/OB have also been documented among youth in Norway 16 , 24 – 26 . However, the reasons behind such inequalities remain poorly understood.…”

“…Studies from the last decade in high-income countries indicate a plateau in the prevalence of OW/OB among youth 11 – 13 . However, looking into subgroups, socioeconomic position (SEP) inequalities in OW/OB among youth continue to widen 14 – 21 , with evidence showing that youth with low SEP have a higher burden of OW/OB or increased body mass index (BMI) than their counterparts with higher SEP.…”