4. respiratory symptoms, social and environmental exposure history and healthcare utilization, assessed by validated questionnaire (ATS-DLD-78-a) Methods Study Setting: This cross-sectional study will be carried out at three Canadian tertiary care pediatric centres (Children's Hospital of Eastern Ontario, Ottawa, Ontario, The Hospital for Sick Children, Toronto, Ontario and Centre Hospitalier Universitaire (CHU) Sainte-Justine, Montreal, Quebec). Ethics approval will be obtained at all participating sites. Analysis: Descriptive statistics will be used to describe the two groups. The primary analysis will be a comparison of signal intensity between children with a history of BPD and those without, adjusting for exposure to earlier (24-26 weeks) or later (27-28 weeks) gestational age, using a two-way analysis of variance. Secondary analyses will examine the association between MRI signal intensity and PFT, as well as signal intensity and respiratory symptoms from the ATS-DLD-78-c questionnaire, using Spearman correlations. Exploratory analyses will also examine the association between PFT and respiratory symptoms, as well as parental smoking exposure, the relationship of obstetrical and neonatal historical factors to signal intensity, PFT, and respiratory symptoms.