1. From the National Center on Birth Defects and Developmental Disabilities (Q-HY and JDE), the National Center for Environmental Health (MG, DK, and SN), and the Coordinating Center for Health Promotion (KS), Centers for Disease Control and Prevention, Atlanta, GA; the Department of Pediatrics, University of Utah, Salt Lake City, UT (LDB); the Department of Medical Genetics, University of British C