Self-Injurious Behaviour during Early Childhood in a General Population Sample – Exploratory Analysis in the Norwegian Mother, Father and Child Cohort Study (MoBa)

Objective Self-harm is one of the strongest risk factors for suicide and a major public health concern. Most existing research has focused on adolescents and adults. Knowledge about the prevalence and correlates of self-harm in children is limited. Method Lived experience interviews informed the analysis plan. In the Norwegian Mother, Father and Child Cohort Study (MoBa), mothers reported on self-injurious behaviour (SIB) at age 3 and 8 years (N=35,494): ‘Does your child ever injure himself/herself deliberately, such as by biting his/her arm or banging his/her head?’. We examined the prevalence of SIB and the prevalence patterns of sociodemographic, neurodevelopmental and mental health factors. Results Mothers answered ‘yes’ on the SIB item at age 3 only (‘ transient ’) for 6.6% ( n =2,336) of the children, 1.2% ( n =434) at 8 years only (‘ emergent ’), and 0.5% ( n =181) at both 3 and 8 years (‘ persistent ’). We observed different patterns of sociodemographic, mental health, and neurodevelopmental factors for all SIB groups compared to No SIB , with individuals in the Emergent and Persistent SIB groups often most distinct from those reporting no SIB. Several factors also distinguished these two groups - most notably rates of paternal depression diagnoses and reports of children's motor developmental delay and sleep problems. Conclusion Groups reporting SIB in childhood had a higher prevalence of mental health and neurodevelopmental conditions. This pattern differed depending on when SIB first emerged and whether it persisted. Future studies should investigate the potential underlying mechanisms for the reported prevalence patterns and their implications for SIB prevention in children.