Rick L. Williams

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To produce more appropriate information for evaluating fetal growth and viability, vital records data were used to compute percentile curves and perinatal, neonatal, and fetal mortality rates at specific birth weights and gestational ages. Percentile values were in good agreement with previous studies, and the large number of births (2,288,806) allowed for(More)
There is increasing interest in estimating and drawing inferences about risk or prevalence ratios and differences instead of odds ratios in the regression setting. Recent publications have shown how the GENMOD procedure in SAS (SAS Institute Inc., Cary, North Carolina) can be used to estimate these parameters in non-population-based studies. In this paper,(More)
BACKGROUND Emerging evidence suggests that nonmedical use (NMU) of prescription attention deficit/hyperactivity disorder (ADHD) medications is rising, but many previous investigations have used clinical or regionally based samples or limited their investigations to stimulants rather than to medications specifically used to treat ADHD. Using an(More)
We compared pregnancy outcomes among United States-born and Mexican-born women having Spanish surnames with US-born Whites and Blacks using California's 1981 matched birth-death cohort file. Maternal risk characteristics between US-born Black women and US-born women with Spanish surnames were similar. In contrast, Latino women, regardless of national(More)
OBJECTIVE The objective of this study was to evaluate the accuracy of the information contained in the Project IMPACT database. Project IMPACT is a comprehensive database system developed to measure and describe the care of intensive care patients. This database is being used by a large group of hospitals to help clinicians improve the care of these(More)
Recent reports indicate that breastfeeding rates continue to be dramatically lower among WIC participants, compared with other US mothers. The WIC Infant Feeding Practices Study was a nationally representative 1-year longitudinal study of WIC participants that obtained information about attitudes regarding infant feeding and about infant-feeding practices.(More)
The rate of cesarean section in California has been growing at a compound rate of about 10 per cent per annum since 1969, coinciding with the advent of fetal monitoring. It is of interest, therefore, to study the distribution and efficacy of obstetric interventions. Information derived from the 1977 California birth cohort and a survey questionnaire was(More)
The gene mutated in the human genetic disorder ataxia-telangiectasia (A-T) has been described recently (Savitsky et al., 1995a) and the complete coding sequence of this gene, ATM, has been reported (Savitsky et al., 1995b). The derived amino acid sequence demonstrates significant homologies to several proteins containing a phosphatidylinositol 3-kinase(More)
To examine further the differences in birth-weight-specific neonatal mortality rates between ethnic groups, we studied causes of death for infants of white, black, United States-born Hispanic, and Mexican-born Hispanic women using linked California birth-death records from 1981 to 1983. Black infants of low birth weight had considerably lower neonatal(More)
To study some of the factors contributing to the higher rate of black neonatal mortality in the United States, we used matched cohort records for California between 1980 and 1981 and for Georgia between 1979 and 1981. We found that at any combination of birth weight and gestational age, black neonates weighing less than 3,000 g had lower mortality rates(More)