The effects of maternal obesity on lung development have been recognized, and speculation is that these diseases are not simply because of accelerated pulmonary decline with aging but with a failure to achieve optimal lung development during early life. These studies tested the hypothesis that maternal obesity alters signaling pathways during the course of lung development that may affect life-long pulmonary health. Adult female mice were fed 60% fat high-fat diet (HFD) or 10% fat control diet (CD) for 8 wk before mating and through weaning. Pup lung tissues were collected at ( ) , , and (after receiving HFD or CD as adults). At , body weights from HFD were greater than CD but lung weight-to-body weight ratios were lower. In lung tissues, NFκB-mediated inflammation was greater in HFD pups at and phospho-/total STAT3, phospho-/total VEGF receptor 2, and total AKT protein levels were lower with maternal HFD and protein tyrosine phosphatase B1 levels were increased. Decreased platelet endothelial cell adhesion molecule levels were observed at and at in the pups exposed to maternal HFD. Morphometry indicated that the pups exposed to maternal or adult HFD had fewer alveoli, and the effect was additive. Decreases in pulmonary resistance, elastance, and compliance were observed because of adult HFD diet and decreases in airway resistance and increases in inspiratory capacity because of maternal HFD. In conclusion, maternal HFD disrupts signaling pathways in the early developing lung and may contribute to deficiencies in lung function and increased susceptibility in adults.