The definition of bronchopulmonary dysplasia: an evolving dilemma

The definition of bronchopulmonary dysplasia (BPD) continues to be a challenging one. The evolution of the disease as well as its definition are discussed. Limitations of the current as well as newer suggested definitions of BPD are summarized. Recognition of the variability of the pulmonary phenotype is a critical aspect of the disease that needs to identified, utilizing biomarkers that will potentially better inform the next iteration of the definition of BPD.