Childhood contact with social services is associated with a range of adverse mental health outcomes across the life course, yet there is limited evidence in relation to self-harm and suicidal or self-harm ideation.

Determine the association between all tiers of childhood contact with social services and presentation to an emergency department (ED) with self-harm or thoughts of suicide or self-harm (ideation) in young adulthood.

This retrospective cohort study linked population-wide administrative data on self-harm and ideation presentations recorded in the Northern Ireland Registry of Self-Harm (NIRSH) between 2012 and 2015 to primary care registrations and children’s social care data. Multilevel logistic regression models estimated the association between level of contact with social services in childhood (no contact; referred but assessed as not in need; child in need and child in care) and ED-presenting self-harm or ideation in young adulthood.

There were 253,495 individuals born 1985–1993 with full data, alive and resident in Northern Ireland during 2012–2015 (ages 18–30 years). Of all young adults that presented to EDs with self-harm or ideation, 40.9% had contact with social services in childhood. Young adults with a history of care had 10-fold increased odds of self-harm or ideation (OR = 10.49 [95% CI, 9.45–11.66]) relative to those with no contact. Even those assessed as not in need of any help or support in childhood were three times more likely to present with self-harm or ideation (OR = 3.45 [95% CI, 3.07–3.88]).

Understanding the magnitude of childhood adversity amongst adults that present to EDs with self-harm or ideation may inform clinicians’ understanding and therapeutic decision-making. Whilst EDs provide an important setting in which to administer brief interventions, a multi-agency approach is required to reduce self-harm/ideation in young adults that had contact with social services in childhood.