Congenital diaphragmatic hernia (CDH) occurs when the diaphragm, the muscle that separates the chest cavity from the abdominal cavity, does not form properly. When an opening is present in the diaphragm, organs that are normally found in the abdomen can move up into the chest cavity. The primary objective of this study is to generate information about the hereditary basis of congenital diaphragmatic hernia and abnormal lung development. Our long-term goal is to identify ways to treat babies in utero with effective but safe drugs to speed up lung development before birth.