Effect of current, lagged and longitudinal exposure to poverty on children's health trajectories in a Québec cohort study

Background: Poverty is one of the most frequently studied indicators of social inequalities in health.  Yet, the impact of poverty across the life course remains under-investigated because of the dearth of longitudinal data.

Objective: To examine trajectories of children’s health before four years old as a function of concurrent, lagged and cumulative exposure to poverty.

Method: Using data from the first four waves of the Quebec Longitudinal Study of Child Development, we performed multilevel logistic and Poisson regressions to fit models for the associations between poverty and the number of acute infections, the number of asthma attacks, accumulation of at least two health problems, and mother’s perception of their child’s health. Poverty was defined according to the Canadian low-income thresholds. Effects of concurrent, one-period-lagged and repeated measures of poverty were estimated, controlling for neonatal, maternal, and environmental characteristics.

Results: Adjusted models indicate that the mean number of infections and the mean number of asthma attacks globally decreased as children were aging. The likelihood being perceived in poor health decreased whereas the likelihood of accumulating at least two health problems did not change across time.

 Concurrent poverty was associated with higher likelihood of being perceived in poor health [Beta=0.368; SE=0.129] or accumulating health problems [Beta=0.287; SE=0.134]. One-period-lagged poverty was associated with higher risk of poor outcomes for all health indicators [Asthma (Beta=0.248; SE=0.081); Infections (Beta=0.095; SE=0.037); Perceived health (Beta=0.320; SE=0.158); and cumulative health problems (Beta=0.248; SE=0.081)]. Longer duration of poverty was associated with more frequent asthma attacks. The association between cumulative poverty and the likelihood of being perceived in poor health was particularly strong at baseline and subsequently remained statistically significant.

Conclusion: Although concurrent, lagged, and cumulative poverty all impact children’s health at least at some time, the effects of lagged poverty are particularly consistent across health indicators and time.