Middle Childhood Morbidity in Children Born Preterm: A Canadian Cohort Study

Objective To assess the risk of middle childhood (ages 5 to 10 years) morbidities among children born preterm. Study design We conducted a population-based cohort study of children born in British Columbia, Canada (2004-2017), followed from ages 5 to10 years. Gestational age (GA) was categorized as 22–28, 29–33, 34–36, 37–41 (reference), and 42–44 weeks. Morbidity outcomes were allergic, cardiac, dermatologic, endocrine, hematologic, renal, neurologic, oncologic, respiratory, rheumatologic, and sleep. Cox proportional hazard models were used to compute adjusted hazard ratios (AHR) and 95% confidence intervals (CIs). Results In the cohort of 510,424 children, 9·50% were born preterm. Morbidity rates ranged from <1·0% (eg, cardiac, gastrointestinal, epileptic, and oncologic) to 16·37% (allergic), with higher rates among children born preterm than at term. A dose-response relationship was observed for several outcomes, with risks increasing as GA decreased. For puberty and disorders of sexual development, AHRs (95% CIs) were 2·17 (1·51–3·11), 1·99 (1·67–2·37), and 1·28 (1·14–1·43) among children born at 22–28, 29–33, and 34–36 weeks, respectively. Corresponding AHRs (95%CIs) for cardiac conditions were 4·20 (2·87–6·14), 1·90 (1·47–2·45), and 1·51 (1·30–1·75); for neurologic conditions 3·20 (2·96–3·46), 1·54 (1·47–1·61), and 1·27 (1·23–1·30); and for respiratory conditions 2·55 (2·33–2·78), 1·52 (1·45–1·60), and 1·23 (1·19–1·26), respectively. Conclusions Children born preterm show elevated morbidity risks at ages 5 to 10. Risks increased with decreasing GA, reinforcing the need for ongoing monitoring and interventions to reduce long-term health complications.