This project is designed to investigate the prenatal maturation of the human lung surfactant system by the analysis of purified surfactant from amniotic fluids. The normal developmental pattern of fetal lung surfactant will be studied by determining changes in lipid and protein composition of surfactant purified by density gradient centrifugation from amniotic fluids obtained at term and at various times during gestation from normal pregnancies. Similar studies will be carried out on surfactant from high risk pregnancies to determine if the composition of surfactant differs from that of normal pregnancies. Of particular interest are pregnancies complicated by diabetes which leads to a high incidence of respiratory distress syndrome. A better understanding of the exact biochemical composition of human lung surfactant and the normal pattern of maturation as well as how the pattern may be altered during high risk pregnancies will serve as the basis for the more rational development of effective measures for the prevention and treatment of hyaline membrane disease.