Potential Challenges: Children will be recruited for this study from neonatal follow-up clinic databases that capture all of those graduating from the neonatal nursery and surviving to 18 months. It is possible that some families may have since relocated or have been lost to follow-up and/or that those willing to participate in a research study at age 7-9 years will differ from those not willing/able to participate. Further, by studying children able to perform PFT and to cooperate for MRI, the investigators will exclude those with significant neurodevelopmental delay, who may also have more severe lung disease. As these are the main study outcomes, however, this will be necessary. Inclusion of children with a history of BPD ensures that those at the more severe end of the spectrum of early pulmonary complications, who are expected to have more severe lung disease, are studied. Exercise testing is another methodology to assess pulmonary and cardiovascular function. It is beyond the feasibility and budget ($200 per test) for this study and also requires coordination tasks that may be challenging for some participants. Nonetheless, it is an important consideration for future work. There are few precedents for pulmonary MRI in children, particularly in those with prematurity and BPD. Traditionally, MRI has been considered suboptimal in comparison to CT for lung parenchyma imaging, due to the low tissue density and loss of signal from magnetic field inhomogeneity at the air lung interfaces. Novel ultra-short echo time (UTE) pulse sequences, however, permit greater signal from the pulmonary parenchyma, which makes MRI a viable strategy to assess emphysematous changes in this population, without exposure to ionizing radiation. In the neonatal intensive care unit, MRI has shown signal decreases suggestive of alveolar simplification (emphysema) in those with severe BPD. It is possible that children with a history of extreme prematurity without BPD will also have some degree of pulmonary parenchymal change on MRI, although it is still expected that abnormalities will be more severe in those with a history of BPD. This study is, however, powered to detect smaller differences in signal intensity between groups than observed in adult COPD studies. The investigators are not using a healthy term control group because the purpose of this research is to assess radiological and functional biomarkers that will help clinicians and researchers identify among preterm born children those at greater risk of long-lasting pulmonary problems who would benefit the most from treatment.