Preterm Birth and Risk of Psychiatric Disorders: A Register-Linkage Cohort Study: Liens entre la naissance prématurée et le risque de troubles psychiatriques : une étude de cohorte avec couplage de registres

ObjectivesThe objectives of this study were to quantify the associations between preterm birth and adolescent-to-adult psychiatric disorders in the Quebec (Canada) population and to determine whether sex and socioeconomic status (SES) modified this relationship.MethodsThis was an observational cohort study using administrative data from the province of Quebec, Canada. All eligible children born preterm between 1976 and 1995 were identified (<i>N</i> = 100,040) and matched 1:2 with term-born children. Individuals were followed from age 11 years until either incident diagnosis of a psychiatric disorder (attention-deficit/hyperactivity disorder [ADHD], psychosis, bipolar disorder, anxiety, or depression), death, or December 2019. Preterm birth was considered as a binary (<37 weeks gestational age) and categorical exposure (extreme, <28; very, 28-31; moderate-to-late, 32-36 weeks gestational age), in addition to continuous gestational age in weeks. Cox proportional hazard models were applied. Effect-modifying roles of sex and SES were investigated in interaction analyses.ResultsCompared to term-born children, those born preterm had a higher risk of all outcomes, with magnitudes ranging from HR 1.16 for ADHD (95% confidence interval 1.13, 1.19) to 1.05 for anxiety (1.04, 1.07). A dose-response relationship was observed, with increasing risks of ADHD, psychosis, and anxiety as the degree of preterm birth increased. Despite some statistically significant associations, there was no clinically significant evidence of effect modification by sex or SES.ConclusionsChildren born preterm had an increased risk of psychiatric disorders in adolescence-to-adulthood, with similar risks across sexes and socioeconomic strata of the population. Policies for early and continued mental health surveillance in this susceptible group are important to initiate appropriate interventions.