A nationwide birth cohort in Japan showed increased risk of early childhood hospitalisation in infants born small for gestational age

Aim: To examine associations between children being born small for gestational age and childhood hospitalisation following term and preterm births. Methods: This study included 34 564 children from a nationwide population-based longitudinal survey starting in 2010, comprising 32 603 term births and 1961 preterm births. Children's hospitalisation history was examined during two observational periods, 6-18 and 6-66 months of age. Logistic regression analysis was conducted, adjusting for child and parental confounders, with children born appropriate for gestational age as reference. Results: Children born small for gestational age were more likely to be hospitalised during early childhood than those born appropriate for gestational age. The odds ratio (95% confidence interval) for hospitalisation from 6 to 66 months of age was 1.19 (1.05-1.34) in term children born small for gestational age and 1.47 (1.05-2.06) for preterm children born small for gestational age, compared with those born appropriate for gestational age. The risk of hospitalisation from 6 to 66 months of age in children born small for gestational age was observed for bronchitis/pneumonia. Conclusion: We observed the adverse effects of small for gestational age on hospitalisation during early childhood in both term and preterm births, particularly for bronchitis and pneumonia.