Association between maternal and paternal mental illness and risk of injuries in children and adolescents: nationwide register based cohort study in Sweden.

Objective: To determine the association between parental mental illness and the risk of injuries among offspring.

Design: Retrospective cohort study.

Setting: Swedish population based registers.

Participants: 1 542 000 children born in 1996-2011 linked to 893 334 mothers and 873 935 fathers.

Exposures: Maternal or paternal mental illness (non-affective psychosis, affective psychosis, alcohol or drug misuse, mood disorders, anxiety and stress related disorders, eating disorders, personality disorders) identified through linkage to inpatient or outpatient healthcare registers.

Main Outcome Measures: Risk of injuries (transport injury, fall, burn, drowning and suffocation, poisoning, violence) at ages 0-1, 2-5, 6-9, 10-12, and 13-17 years, comparing children of parents with mental illness and children of parents without mental illness, calculated as the rate difference and rate ratio adjusted for confounders.

Results: Children with parental mental illness contributed to 201 670.5 person years of follow-up, while children without parental mental illness contributed to 2 434 161.5 person years. Children of parents with mental illness had higher rates of injuries than children of parents without mental illness (for any injury at age 0-1, these children had an additional 2088 injuries per 100 000 person years; number of injuries for children with and without parental mental illness was 10 235 and 72 723, respectively). At age 0-1, the rate differences ranged from 18 additional transport injuries to 1716 additional fall injuries per 100 000 person years among children with parental mental illness compared with children without parental mental illness. A higher adjusted rate ratio for injuries was observed from birth through adolescence and the risk was highest during the first year of life (adjusted rate ratio at age 0-1 for the overall association between any parental mental illness that has been recorded in the registers and injuries 1.30, 95% confidence interval 1.26 to 1.33). Adjusted rate ratios at age 0-1 ranged from 1.28 (1.24 to 1.32) for fall injuries to 3.54 (2.28 to 5.48) for violence related injuries. Common and serious maternal and paternal mental illness was associated with increased risk of injuries in children, and estimates were slightly higher for common mental disorders.

Conclusions: Parental mental illness is associated with increased risk of injuries among offspring, particularly during the first years of the child's life. Efforts to increase access to parental support for parents with mental illness, and to recognise and treat perinatal mental morbidity in parents in secondary care might prevent child injury.