Could increasing income in lone-parent households reduce inequality in child mental health problems?

Abstract

Abstract Half of lone-parent families in the UK live in relative poverty (income <60% national median) compared to a quarter of two-parent families. Family hardship is associated with increased risk of child mental health problems (CMHP). Using data from the UK Millennium Cohort Study (∼18,000 children born 2000-02), we investigated whether equalising income between lone- and two-parent households could reduce prevalence and inequality in CMHP. Exposure was family structure (lone-/ two-parent household) at 9 months; mediator was equivalised weekly household income at 3 years(y); outcome was parent-report CMHP at 5y (Strengths and Difficulties Questionnaire; normal/ borderline-abnormal). The analytic sample comprised 11,193 children. We modelled the relationship between family structure, income and CMHP in logistic marginal structural models, weighted for attrition to MCS at 5y, and adjusted for baseline and intermediate confounding. Prevalence of CMHP was assessed overall and according to family structure. Differences between lone and two-parent households were represented by risk ratios (RRs) and differences (RDs) [95% CIs]. We modelled a hypothetical increase in income for all lone-parent households, so that median income was equalised between lone- and two-parent households, and re-estimated prevalence, RRs and RDs. Prevalence of CMHP was 8.5%. Children from lone-parent households were more likely to exhibit CMHP (RR 1.73[1.28-2.19]; RD 5.70[2.44-8.97]). Equalising income reduced prevalence (8.2%), and differences in CMHP by family structure (RR, 1.37[0.90-1.83]; RD, 2.86[-0.06-6.31]). Sensitivity analyses showed that associations between exposure, mediator and outcome were comparable in more recent MCS sweeps, indicating that these relationships still hold today. Inequalities in CMHP between lone- and two-parent families in the UK are large. Levelling up income for lone-parents households could reduce differences in child mental health problems related to family structure. Key messages Inequalities in CMHP between lone- and two-parent families in the UK are large. Levelling up income for lone-parents households could reduce differences in child mental health problems related to family structure.