Prematurity at birth and risk of self-injury, overdose or death in adolescence and early adulthood: a population-based cohort study

Background — Preterm birth may adversely affect cortical brain development, and subsequent cognition in childhood and adolescence. Such abnormalities in brain development are correlated with suicidal and non-suicidal self-injury and persistent substance use, and to unintentional injury as well.

Objective — To evaluate the risk of self-injury, overdose, and all-cause mortality among adolescents and young adults – each in relation to preterm birth.

Design — Population-based cohort study in Ontario, Canada, where there is universal healthcare for all.

Setting — All of Ontario, Canada, where there is universal healthcare.

Participants — All youths born in Ontario from 1992 to 2012, and alive at age 10 years.

Exposures — Degree of prematurity in 2-week earlier increments, as well as preterm birth < 37 weeks’ gestation.

Outcomes — i) Primary composite of an ED visit or hospitalization for intentional self-injury, poisoning or overdose, or all-cause mortality; and ii) co-primary composite of intentional self-injury, poisoning or overdose – each assessed between ages 10–24 years.

Results — Among 2352,563 youths in the cohort, 151,182 (6.4 %) were born preterm. Adjusted hazard ratios (aHR) for i) self-injury, overdose, or all-cause mortality was 1.03 (95 % CI 1.01–1.05) per 2-week earlier gestational age at birth; and ii) 1.01 (95 % CI 0.99–1.03) for self-injury or overdose. Compared to term births, preterm birth < 37 weeks’ gestation was associated with a higher aHR for i) self-injury, overdose or all-cause mortality (1.09, 95 % CI 1.05–1.12); and ii) self-injury or overdose (1.06, 95 % CI 1.02–1.10).

Conclusion — Preterm birth may be associated with a slightly higher risk of all-cause mortality and, possibly, self-injury and overdose among adolescents and young adults. Ongoing efforts might focus on the health of youths who were born prematurely as they enter their adolescent years.