Impact of moving into poverty on maternal and child mental health: longitudinal analysis of the Millennium Cohort Study

BackgroundThe UK Government has recently questioned whether relative measures of income poverty effectively reflect children's life chances. Although relative poverty is associated with poor maternal and child mental health, few studies have assessed the impact of moving into poverty on mental health outcomes. To inform this debate, we explored the association between transitions into poverty and mental health among children and their mothers using a nationally representative sample of children in the UK followed up between 2000 and 2012.MethodsOur analysis of the UK Millennium Cohort Study was based on 5877 singletons who participated in sweeps of the study at ages 9 months to 11 years and were not in relative poverty nor had maternal and child mental health problems when these measures were first recorded at 3 years old. The main outcomes were maternal psychological distress (Kessler Psychological Distress scale, K6) and child socioemotional behavioural problems (Strengths and Difficulties Questionnaire) at ages 5, 7, and 11 years. The main exposure of interest was moving into relative poverty, defined as household equivalised income less than 60% of median household income, according to the Organisation for Economic Co-operation and Development equivalence scale. Using discrete time-hazard models, we estimated odds ratios for subsequent maternal and child mental health of new transitions into poverty, while adjusting for baseline confounding. We further assessed how maternal mental health mediated any impact on child mental health.FindingsOverall 904 families (15·4%) experienced a new transition into poverty. After adjustment for confounders, transition into relative poverty increased the odds of maternal psychological distress (odds ratio 1·86, 95% CI 1·51–2·29) and socioemotional behaviour problems in children (1·37, 1·02–1·85). Controlling for maternal psychological distress reduced the odds of socioemotional behavioural problems in children, and rendered the association non significant (adjusted odds ratio 1·26, 95% CI 0·92–1·72).InterpretationIn this UK cohort, transitions into relative poverty, by use of the currently contested income-based definition, were associated with an increase in the risk of child and maternal mental health problems. Maternal mental health appeared to mediate the association between poverty transitions and child mental health. Actions to address child poverty are needed to tackle the mental health crisis in children in the UK.FundingSW, BB, and DT-R are funded by the Wellcome Trust.