Mediation by parent health literacy and behaviour of socioeconomic inequality in child overweight

Background: Socioeconomic health inequalities exist in childhood overweight. Understanding what factors mediate this relationship could help reduce these inequalities. Therefore, we aimed to study to what extent and how parental health literacy and parental health behaviours mediate the relationship between parental socioeconomic status and childhood overweight. 
Methods: Data were from the multigenerational prospective Dutch Lifelines Cohort Study. The sample consisted of 6,683 children aged 12.8 years (SD 2.6) at baseline with an average follow-up of 36.2 months (SD 9.3). We used causal mediation analyses to assess to what extent parental health literacy and health behaviours (smoking, diet quality, physical activity, and alcohol intake) mediated the relationship between parental socioeconomic status (education, income, and occupation) and childhood overweight (age- and sex-specific definition). 
Results: An additional four years of parental education decreased the odds of childhood overweight by 42%. Similarly, a SD increase in income and occupation reduced the odds of childhood overweight by 12% and 20%, respectively. Only parental smoking independently mediated these relationships; it explained 6.6% (education) and 5.7% (occupation) of these pathways. However, all parental health behaviours together explained 8.4% (education), 19.4% (income), and 9.8% (occupation) per pathway. Lastly, adding parental health literacy explained 10.8% (education), 27.4% (income), and 13.3% (occupation) of these pathways.
Conclusions: We found large socioeconomic inequalities in childhood overweight, the largest for education. Remarkably, smoking was the most relevant parental health behaviour explaining inequalities in childhood overweight. Smoking could serve as an important target for interventions to reduce socioeconomic inequalities in childhood overweight.