The fetal lung progresses through a series of orchestrated developmental events that ultimately leads to a structurally and a functionally mature lung at term birth. However, a number of insults during fetal gestation can lead to aberrant lung growth and/or lung injury. The focus in this chapter is on events that occur after the fetus is of viable gestation rather than the early embryonic insults that ultimately lead to bronchopulmonary dysplasia, lung hypoplasia, or other clinically relevant adverse lung outcomes. Reviews of experimental animal studies are presented in the context of how these studies inform us of likely pathways of lung injury documented in clinical studies. The major perinatal insults discussed are chorioamnionitis, drugs and toxins, and intrauterine growth restriction or nutritional insults. The chapter also integrates how the developmental immune system modulates the lung injury and inflammation that leads to poor functional lung outcomes.