The Biostatistics Center of the Department of Statistics and Computer Information Systems, George Washington University, requests a five-year renewal of the Cooperative Agreement number 5-UlO-HD-19897-05, "Chorionic Villus Sampling vs. Amniocentesis Study - Data Center". The application proposes a continuation of the Biostatistics Center's Data Coordinating Center activities for four major continuing projects listed below, and a new NICHD study of the effects of infant day care on child development, beginning during the current year. The major ongoing projects for which we request renewal are: 1.The Chorionic Villus Sampling and Amniocentesis Study, now in its final stages of data collection for two major studies, and currently involved in extensive data analysis activities; 2.The Maternal Fetal Medicine Units Network, currently conducting three clinical trials; 3.The Neonatal Intensive Care Units Network, currently conducting two clinical trials and a registry of low birthweight infants; and 4.The RADIUS Study, a clinical trial in its third year. A general section of the application describes data coordinating center methods which apply to all projects. The scientific aims, progress to date, and experimental design and methods for the 5-year period, are given in separate sections specific to each project.