Medical and surgical care have made considerable progress in the last two decades in the care of the mother, fetus, and neonate. Most of the improvement in outcomes has been related to advances in diagnostic and therapeutic modalities. These advances have only been possible due to dramatic progress in our knowledge of the physiological mechanisms that determine the normal development of organ systems, as well as the alterations that can lead to disease states and their multifarious consequences. Because improved antenatal care has resulted in the survival of greater numbers of immature infants, they have become a major challenge for clinicians due to the immaturity of multiple organs and their susceptibility to long-term sequelae. The aim of this book is not to address all aspects related to the newborn lung, but to discuss those areas that are more novel or controversial or have been of greater relevance in the progress of maternal, fetal, and neonatal care. Where possible, we have attempted to meet the expectation that practice guidelines be based either on convincing available evidence or on consensus statements of authoritative organizations. Therefore, this book should be useful to obstetricians, perinatologists, and neonatologists.