Congenital lung malformations (CLM) consist of a broad range of conditions that can affect a developing baby. These conditions can range from small asymptomatic cystic lung lesions to large lesions which may require treatment while your baby is still inside mom (in utero). The most common of these lesions are bronchopulmonary sequestration and congenital pulmonary airway malformation (which used to be called cystic adenomatoid malformation –CCAM). In normal development, babies will have three lobes of the lung of the right and 2 lobes on the left. Most CLM usually arise from a single lobe but, rarely, they can affect multiple lobes. If a single lobe is involved, the most common location is in the lower lobes.The diagnosis and management of these lesions can be challenging in the prenatal period. Some of these babies may require urgent fetal intervention, so a thorough understanding of the possible treatment strategies is crucial for successful management of these patients.