Is sexual maturity occurring earlier among U.S. children?

Purpose: To compare the onset and completion of sexual maturation among U.S. children between 1966 and 1994.

Heritability of age at menarche in girls from the Fels Longitudinal Study.

Menarche is the hallmark maturational event of female childhood. Many studies indicated a significant genetic contribution to the timing of the onset of menstruation, but most of these studies were limited by the use of retrospective data and by the use of data from only certain types of relatives (i.e.

Age at menarche and racial comparisons in US girls.

Background: Concern regarding change in the onset of sexual maturation of US girls has increased the need for current information on age at menarche from a national sample. Previous reports have been sparse and interpretation has been limited because of the racial composition and ages of the samples.

Objective: The objectives of this study were to estimate the distribution of age at menarche for all US girls and for non-Hispanic white, black, and Mexican American girls in the Third National Health and Nutrition Examination Survey and to test for racial differences.

National estimates of the timing of sexual maturation and racial differences among US children.

Objective: To provide clinically meaningful, normative reference data that describe the timing of sexual maturity indicators among a national sample of US children and to determine the degree of racial/ethnic differences in these estimates for each maturity indicator.

Methods: Tanner staging assessment of sexual maturity indicators was recorded from 4263 non-Hispanic white, black, and Mexican American girls and boys aged 8.00 to 19.

Predicting overweight and obesity in adulthood from body mass index values in childhood and adolescence.

Background: The Centers for Disease Control and Prevention (CDC) introduced the clinical use of the body mass index (BMI; in kg/m(2)) in growth charts for young males and females.

Objective: This study updates our previous report with the use of new CDC BMI charts and definitions of adult overweight and obesity to predict adult overweight or obesity.

Design: Logistic models were fitted to relate adult overweight and obesity to childhood and adolescent BMI values at each age for 166 males and 181 females in the Fels Longitudinal Study and were applied to predict adult overweight and obesity at the 75th, 85th, and 95th percentiles on the CDC charts of childhood and adolescent BMI.

2000 CDC Growth Charts for the United States: methods and development.

Objectives: This report provides detailed information on how the 2000 Centers for Disease Control and Prevention (CDC) growth charts for the United States were developed, expanding upon the report that accompanied the initial release of the charts in 2000.

Methods: The growth charts were developed with data from five national health examination surveys and limited supplemental data. Smoothed percentile curves were developed in two stages.

Centers for Disease Control and Prevention 2000 growth charts for the United States: improvements to the 1977 National Center for Health Statistics version.

Objective: To present a clinical version of the 2000 Centers for Disease Control and Prevention (CDC) growth charts and to compare them with the previous version, the 1977 National Center for Health Statistics (NCHS) growth charts.

Methods: The 2000 CDC percentile curves were developed in 2 stages. In the first stage, the empirical percentiles were smoothed by a variety of parametric and nonparametric procedures.

Statistical effects of varying sample sizes on the precision of percentile estimates.

The present study evaluates the precision of outlying percentile estimates, with age- and sex-associated variations and facilitates decisions needed to revise the current NCHS 1977 Growth Charts with regard to 1) the inclusion of 3(rd) and 97(th) percentiles and 2) the selection of survey data for the construction of the revised growth charts. Simulation was performed to obtain data with distribution characteristics similar to those of The Third National Health and Nutritional Examination Survey (NHANES III) (1988-1991) data. NHANES III consists of a two-phase, 6-year, complex stratified multistage probability cluster, cross-sectional survey conducted from 1988 through 1994 to represent the US noninstitutionalized population.

Weight, stature, and body mass index data for Mexican Americans from the third national health and nutrition examination survey (NHANES III, 1988-1994).

Selected age- and sex-specific percentiles are presented for 4,054 Mexican American children ages 1-18 years who were included in the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994). These percentile values are compared with corresponding percentiles for Mexican Americans from the Hispanic Health and Nutrition Examination Survey (HHANES, 1982-1984). In each sex, the weight and weight/stature(2) percentiles from NHANES III were significantly larger than those from HHANES.

Serial changes in blood pressure from childhood into young adulthood for females in relation to body mass index and maturational age.

This study determines: (1) patterns of change from childhood to young adulthood in body mass index (BMI), systolic blood pressure (SBP), and diastolic blood pressure (DBP), (2) effects of elevated BMI values on changes in blood pressures (BP), (3) extent of tracking for SBP, DBP, and BMI, and (4) prediction of future risk for elevated BP from earlier values. Annual serial BP and BMI data were available for 198 white females, ages 8-22 years, enrolled in the Fels Longitudinal Study. Patterns of change in BMI were described by a random effects model with a time series model for the correlated residuals.

Decanalization of weight and stature during childhood and adolescence.

The probabilities that children and adolescents alter their positions to non-adjacent canals (decanalization) on the current NCHS growth charts have been estimated. In this context, canals are the zones between the major percentile levels (5th, 10th, 25th, 50th, 75th, 90th, and 95th) that are shown on the charts. These probabilities were calculated for one- and 2-year intervals, beginning at each annual age from 3-16 years, using serial data for weight and stature from 329 male and 303 female participants in the Fels Longitudinal Study.

The decanalization of weight, recumbent length, and head circumference during infancy.

This study has estimated the extent to which 659 infants in the Fels Longitudinal Study maintained their positions in canals on the current NCHS growth charts during 6- and 12-month intervals. These canals are the zones between adjacent major percentile lines (5th, 10th, 25th, 50th, 75th, 90th, and 95th) on the growth charts. The probabilities of increases or decreases in level by two or more canals were calculated.

Longitudinal assessment of hormonal and physical alterations during normal puberty in boys. IV: Predictions of adult height by the Bayley-Pinneau, Roche-Wainer-Thissen, and Tanner-Whitehouse methods compared.

To determine how accurately the Roche-Wainer-Thissen (RWT), Tanner-Whitehouse (TW2), and Bayley-Pinneau (BP) prediction models estimated adult height, serial height predictions were made for 23 healthy boys (mean initial age 10.4 ± 1.1 years) every 8 months from 8-15 years of age.

Relationship of skeletal age to limb composition during pubescence.

The relationships between skeletal age (SA) and limb composition (arms, legs, and all four limbs) in terms of fat mass (FM), fat-free mass (FFM), muscle mass (MM) and bone mineral content (BMC) were investigated in 55 males and 53 females aged 9-15 years. The Fels method was used to assess hand-wrist SAs which were expressed as SA/chronological age (SA/CA). The limb composition data were obtained from a Lunar dual-energy x-ray absorptiometer using 3.

Reference data for arm muscle and arm adipose tissue areas in Mexican Americans from the Hispanic Health and Nutrition Examination survey (HHANES 1982-1984): Comparisons with whites and blacks from NHANES II (1976-1980).

Data for arm muscle area (AMA) and arm adipose tissue area (AATA) from 3695 Mexican American children 6 months to 18 years of age included in HHANES (1982-1984) were used to obtain age-and gender-specific means and selected percentiles. These statistics were compared with those for non-Hispanic white and non-Hispanic black children from NHANES II (1976-1980). In comparison with non-Hispanic white and non-Hispanic black children, the Mexican American children tended to have smaller means and percentile values for AMA but larger values for AATA.

Head circumference for Mexican American infants and young children from the Hispanic health and nutrition examination survey (HHANES 1982-1984): Comparisons with Whites and Blacks from NHANES II (1976-1980).

This study presents descriptive statistics for head circumference in Mexican American children 6 months to 7 years of age using data from the Hispanic Health and Nutrition Examination Survey (HHANES, 1982-1984) and compares these statistics with national estimates of head circumference for non-Hispanic White children and non-Hispanic Black children from the Second National Health and Nutrition Examination Survey (NHANES II, 1976-1980). Head circumference was measured in the same standardized fashion in the two surveys. The patterns of change with age in means and in empirical percentiles were similar for both genders and for all three ethnic groups.

Sarcopenia: A critical review of its measurements and health-related significance in the middle-aged and elderly.

A summary of the work performed by Stanley Garn relating to muscle mass while he worked at the Fels Research Institute is followed by a critical review of the measurement of sarcopenia, which is a deficiency of muscle mass, and its implications for health. The only satisfactory data for total muscle mass come from one cadaver study of a small selected sample. Analyses in relation to health (mortality rates) are limited to indices of muscle mass of which the body mass index (BMI) and arm muscle area or circumference are the most important because large amounts of serial data are available for analysis.

Family resemblance for Preece-Baines growth curve parameters in the fels longitudinal growth study.

The Preece-Baines Model 1 (PB1) nonlinear regression equation was fit to serial stature measurements from 456 participants in the Fels Longitudinal Growth Study. The resulting model parameters and derived biological parameters, such as age, stature, and velocity at take-off (TO) and peak velocity (PV) are analyzed for family resemblance in 228 nuclear families through estimation of familial correlations and path coefficients. Significant family resemblance was found for all of the growth parameters.

Mathematical modelling of human growth: A comparative study.

Kernel regression is a nonparametric procedure that provides good approximations to individual serial data. The method is useful and flexible when a parametric method is inappropriate due to restricted assumptions on the shape of the curve. In the present study, we compared kernel regression in fitting human stature growth with two models, one of which incorporates the possible existence of the midgrowth spurt while the other does not.

Development of reference data for increments in variables related to growth.

This paper directs attention to the progress made during the last few decades in methods for the development of reference data for increments and in the application of such data. This progress is exemplified by analyses of increments in recumbent length during infancy based on data from the Fels Longitudinal Study that have led to the development of reference data that can be applied easily to individuals and groups. The methods used to develop incremental reference data have improved considerably, but further progress is needed to construct better models, to refine the procedures for fitting models, and to simplify the application of incremental reference data.

Model fitting to early childhood length and weight data from the fels longitudinal study of growth.

Length and weight data from 3 months to 6 years of age from 466 participants in the Fels Longitudinal Study of Growth were used to fit the Jenss non-linear growth curve. Six (1%) of the Fels participants had extremely outlying values for length parameters, and 20 (4%) had outlying values for weight parameters. The general pattern in the outliers is for average or below average size in infancy, followed by unusually rapid growth or weight gain in childhood.

Family resemblance for patterns of growth in early childhood.

Parameters of the Jenss curve representing linear and non-linear components of growth in early childhood were fitted to longitudinal recumbent length and weight measurements from participants in the Fels Longitudinal Growth Study. Nuclear family correlations were estimated for each of four Jenss parameters (a linear intercept and slope and a non-linear intercept and degree of curve) for length and for weight. The TAU path model was fit to the correlations, in order to estimate path coefficients representing transmissibility from parent to child (t ) and non-transmissible sibling resemblance (s).

X-linked pattern of inheritance for serial measures of weight/stature.

The pattern of family resemblance for long-term serial measures of weight/stature (W/S ) in approximately 500 individuals from the Fels Longitudinal Growth Study suggests that X-linked genes may be contributing to the variability in this trait among children, particularly during the prepubertal age range of 2-9 years. In this data set, W/S was measured serially at the same ages in all family members. Thus, a parent-child correlation at a specific age can be determined even though the measurements were made on the child a generation later than on the parent.

Relative utility of carpal skeletal ages.

The need to assess the carpal bones when a skeletal age is being obtained for a handwrist radiograph has been determined. The mixed longitudinal data that were analyzed had been obtained from 335 boys and 322 girls at 1, 4, 7, 10, 13, and 16 years of age. The FELS assessment method, which was used to obtain the skeletal ages, provides the standard error of each assessment; each of these standard errors is determined by the amount of relevant information available from a radiograph.