Household income and children's mental health outcomes: the mediating role of maternal wellbeing and parent-child relationship quality.

Uncertainty remains about the mechanism(s) through which household income influences mental health across the life course. The family stress model suggests the role of parental mental health and child-parent relationship quality may be significant, however few studies have explored this longitudinally. The present study aimed to decompose the pathways from low household income at age 3 to children's mental wellbeing at age 6, via maternal wellbeing (age 4) and parent-child relationship quality (age 5). We included four sweeps of the Growing Up in Scotland Study (n = 3639). Weights and multiple imputation were used. Low income was defined as the two bottom quintiles of equivalised household income. Potential mental health difficulties were determined using the Strengths and Difficulties Questionnaire. Mediators were assessed using the Depression, Anxiety and Stress Scale and the Pianta Child-Parent Relationship Scale. A causal mediation analysis was conducted. Confounding factors adjusted for included ethnicity, family type, maternal age, education and employment. Children from low-income households at age 3 were more than twice as likely to have a potential mental health difficulty at age 6 compared to all other children (adjusted odds ratio (OR) 2.16 (95% CI 1.50 to 3.80). Reduced maternal wellbeing mediated 11.21% of the total effect. Adding perceived child-parent relationship quality to this model increased the proportion mediated to 30.89%. Increasing the incomes of young families will improve child mental health. Given the long-term risks associated with childhood mental health difficulties this should be a public health priority.