This project uses data from the NINCDS Collaborative Perinatal Project to investigate the relation of selected factors which may affect the mothers during pregnancy, with the occurrence of congenital heart defects in the children. Observations on some 50,000 pregnancy records provide case and control data for analysis. Some 460 children have been identified as having definite congenital cardiac anomalies. These include cardiac conditions which are part of known syndromes. Analysis considers the problem as a whole, but also separates the various anomalies to clarify possible etiologies.