Trajectories of socioeconomic status across children's lifetime predict health.

OBJECTIVE: Socioeconomic status is one of the most robust social factors associated with health, but the dynamics of how socioeconomic status over time affects children's health remains unclear. This study tested how various models of childhood socioeconomic status (accumulation, change, variability, and critical periods of family income) would predict health outcomes at a final time point in childhood.
METHODS: This was a prospective, longitudinal study of 6306 children who were aged 10 to 11 years and whose families were interviewed every other year from birth onward. The sample came from the US National Longitudinal Survey of Youth-Children. In the same data set, a replication sample of 4305 14- to 15-year-old children was also examined. Primary outcomes included parent report of asthma and conditions that limited activity and school and required physician treatment.
RESULTS: Lower cumulative family income was associated with higher odds for having a condition that limited childhood activities, as well as a condition that required treatment by a physician at ages 10 to 11. Cumulative family income was a stronger predictor than change in income or variability in income. Lower family income early in life (ages 0-5 years) was associated with higher odds for having a condition that limited activities and a condition that required treatment by a physician at ages 10 to 11, independent of current socioeconomic status. Findings were replicated in the 14- to 15-year-old sample.
CONCLUSIONS: These findings suggest that the accumulation of socioeconomic status in terms of family income across childhood is more important than social mobility or variability in socioeconomic status, although there may be certain periods of time (early life) that have stronger effects on health. These findings suggest the importance of childhood interventions for reducing health disparities.