1. Pediatric Medical Officer, Perinatal Biology and Infant Mortality Branch, National Institute of Child Health and Human Development, National Institutes of Health, United States Public Health Service, Bethesda, Md. 20014; Department of Pediatrics, University of California, San Diego, University Hospital, San Diego, Calif. 92103.
2. Office of Program Operations, Department of Health, Education and Welfare, Parklawn Building, Rockville, Md.
3. Perinatal Biology and Infant Mortality Branch, National Institute of Child Health and Human Development, National Institutes of Health, United States Public Health Service, Bethesda, Maryland 20014.