Association between household poverty dynamics and childhood overweight risk and health behaviours in the United States: a 8-year nationally representative longitudinal study of 16800 children.

Abstract

No study has examined how the pattern of income dynamics influences both of children's body mass index (BMI) trajectory and health behaviours. To examine the association between household poverty dynamics and childhood overweight risk in the USA. Using the longitudinal data of 16800 children (from kindergarten to the 8th grade) in the nationally representative US cohort-Early Childhood Longitudinal Study, Kindergarten Class 1998-1999, we examined the differences in BMI trajectory, weight-related health behaviours and risk of overweight in association with household poverty dynamics during follow-up (never [no experience of poverty], transient [once], recurrent [≥2 times] and persistent poor [remained]) using mixed models with fractional polynomial functions and estimating equation models. Overall, children experiencing poverty were more likely to have adverse BMI growth trajectory and eating and sedentary behaviours compared with the never poor. The recurrently poor children (12.8%) had the fastest BMI trajectory, highest overweight/obesity prevalence from 5 to 16years old and highest proportion of excessive soda/fast food consumption and irregular exercise at 8th grade than did others (p<0.05). The persistently poor (8.4%) were the lowest in BMI growth trajectory but became the second highest in childhood obesity through a steady increase in BMI over time. Children in the recurrently poor group had a 1.5 times (95% CI=1.0-2.2) higher risk of overweight than those having never experienced poverty during follow-up. The experience of recurrent household poverty had a significant association with children's adverse eating behaviours and increased obesity risk subsequently.