Multiple trajectories of family adversity and poverty and adolescent self-harm and suicide attempts: findings from the UK Millennium Cohort Study

Background Exposure to family adversities including domestic violence, parental mental ill-health, and poverty in childhood increases the risk of self-harm and suicide attempts in adolescents. However, few studies have assessed the influence of clustered family adversity and poverty trajectories throughout childhood on self-harm behaviours and suicide attempts. Methods In this population-based longitudinal study, we used data on 9316 children from the UK Millennium Cohort Study. Exposure trajectories of poverty and family adversities were characterised using group-based multi-trajectory models (age 9 months−14 years). Multivariable logistic regression models were used to examine the association of trajectories with self-harm and suicide attempts at age 17. Population-attributable fractions were calculated to quantify the contribution of family adversity and poverty to the outcomes at the country level. Results Of 9316 participants, 2087 (22.4%) reported self-harm behaviours and 659 (7.1%) had made a suicide attempt. Compared with children experiencing low poverty and adversity, children in the persistent adversity groups were more likely to report both self-harm and suicide attempts; those exposed to persistent poverty and poor parental mental health were particularly at increased risk of self-harm (OR = 1.71, 95% CI: 1.30–2.24) and suicide attempts (OR = 3.98, 95% CI: 2.76–5.74). Overall, we estimated that about 13.2% of self-harm behaviours and 36.9% of suicide attempts were attributable to persistent family adversities and poverty. Conclusions Children growing up with persistent exposure to family adversities and poverty are more likely to harm themselves and attempt suicide, particularly those who experience the combination of persistent poverty and long-term poor parental mental health. Early detection of children at risk and intervention such as anti-poverty approaches to prevent long-lasting adversities are key to alleviating risky behaviours in UK adolescents.