CDC growth charts: United States.

OBJECTIVES: This report presents the revised growth charts for the United States. It summarizes the history of the 1977 National Center for Health Statistics (NCHS) growth charts, reasons for the revision, data sources and statistical procedures used, and major features of the revised charts. METHODS: Data from five national health examination surveys collected from 1963 to 1994 and five supplementary data sources were combined to establish an analytic growth chart data set. A variety of statistical procedures were used to produce smoothed percentile curves for infants (from birth to 36 months) and older children (from 2 to 20 years), using a two-stage approach. Initial curve smoothing for selected major percentiles was accomplished with various parametric and nonparametric procedures. In the second stage, a normalization procedure was used to generate z-scores that closely match the smoothed percentile curves. RESULTS: The 14 NCHS growth charts were revised and new body mass index-for-age (BMI-for-age) charts were created for boys and girls (http://www.cdc.gov/growthcharts). The growth percentile curves for infants and children are based primarily on national survey data. Use of national data ensures a smooth transition from the charts for infants to those for older children. These data better represent the racial/ethnic diversity and the size and growth patterns of combined breast- and formula-fed infants in the United States. New features include addition of the 3rd and 97th percentiles for all charts and extension of all charts for children and adolescents to age 20 years. CONCLUSION: Created with improved data and statistical curve smoothing procedures, the United States growth charts represent an enhanced instrument to evaluate the size and growth of infants and children.

Dietary calcium, alcohol, and incidence of treated hypertension in the NHANES I epidemiologic follow-up study.

Evidence concerning the relation between dietary calcium intake and development of hypertension is inconsistent. Some of this inconsistency may be due to interaction of this relation with other factors. The current study was designed to test for an interaction between alcohol consumption and the relation of dietary calcium intake to 10-year incidence of hypertension in a sample of the US adult population: the Epidemiologic Follow-up Study (1982-1984) of the First National Health and Nutrition Examination Survey (NHANES I) (1971-1975). Interactive logistic regression models were estimated with incident hypertension defined as self-reported treatment with antihypertensive medication. After exclusion of participants with evidence of hypertension at baseline (resulting n = 6,634), odds ratios for hypertension were estimated for each 1-g/day increase in calcium intake. The relation between dietary calcium and incident hypertension showed significant interactions with frequency of alcohol use (odds ratio (OR) = 1.33 for daily drinkers, OR = 0.84 for others; p = 0.005 for difference), age (OR = 0.75 for < or = 40 years at baseline, OR = 1.00 for > 40 years; p = 0.004), and body mass index, defined as weight (kg) divided by height (m) squared (OR = 0.82 for < or = 26, OR = 1.01 for > 26; p = 0.018). Interactions with sex and race (black vs. white) were not significant (p > or = 0.4). These findings suggest that a protective effect of foods containing calcium on the risk of developing hypertension may vary across levels of alcohol consumption and other risk factors for hypertension.

A note on the analysis of parity progression ratios.

Contingency table modeling procedures are proposed to examine the effects of independent variables on parity progression ratios. The methodology is outlined and an incremental-factorial linear model is developed.