Childhood overweight and cardiovascular disease risk factors: the National Heart, Lung, and Blood Institute Growth and Health Study.

OBJECTIVE: To estimate the prevalence and incidence of overweight in African-American and Caucasian girls, and to examine associations between adolescent overweight and cardiovascular disease (CVD) risk factors. STUDY DESIGN: In the National Heart, Lung and Blood Institute Growth and Health Study (NGHS), annual measurements were obtained from girls followed longitudinally between age 9 or 10 and 18 years; self-reported measures were obtained at age 21 to 23 years. A total of 1166 Caucasian girls and 1213 African-American girls participated in the study. Childhood overweight as defined by the Centers for Disease Control and Prevention (CDC) was the independent variable of primary interest. Measured outcomes included blood pressure and lipid levels. RESULTS: Rates of overweight increased through adolescence from 7% to 10% in the Caucasian girls and from 17% to 24% in the African-American girls. The incidence of overweight was greater at age 9 to 12 than in later adolescence. Girls who were overweight during childhood were 11 to 30 times more likely to be obese in young adulthood. Overweight was significantly associated with increased percent body fat, sum of skinfolds and waist circumference measurements, and unhealthful systolic and diastolic blood pressure, high-density lipoprotein cholesterol, and triglyceride levels. CONCLUSION: A relationship between CVD risk factors and CDC-defined overweight is present at age 9.

Pubertal correlates in black and white girls.

OBJECTIVES: Since pubertal maturation is an important covariate in studies that evaluate physical and social changes that occur during the teen years, we examined pubertal parameters in a group of US girls. STUDY DESIGN: Black and white girls recruited at age 9 were followed annually for 10 years. Preece-Baines model 1 was used to estimate tempo and growth parameters. The temporal trend between age of menarche and onset of puberty was calculated. RESULTS: The study included 615 (77.2% prepubertal) white and 541 (49.4% prepubertal) black participants. Mean onset of puberty was 10.2 and 9.6 years in white and black girls, respectively, menarche was 12.6 and 12.0, achievement of Tanner growth stage 5 was 14.3 and 13.6, and achievement of adult height was 17.1 and 16.5 years. The Pearson's correlation coefficient between menarche and onset of puberty was .37. CONCLUSIONS: Menarche is often used as a marker for onset of puberty and for timing of puberty. Data gathered over the past 20 years suggest only moderate correlation between menarche and onset of puberty (.37-.38), which has decreased significantly during the last 50 years. This suggests the existence of both similar and unique factors that impact the age at onset of puberty and age at menarche.

Sex hormones and the changes in adolescent male lipids: longitudinal studies in a biracial cohort.

OBJECTIVE: To determine the role of increasing free testosterone and estradiol in pubertal changes in male lipids. METHODS: We conducted a 3-year, longitudinal, observation study with biannual visits of 251 black and 285 white boys who were 10 to 15 years of age at enrollment. Sex hormones, lipid parameters, and body composition measures were obtained according to a standard protocol. The body mass index (kg/m(2)) was used to characterize obesity. RESULTS: White boys had higher triglycerides, lower high-density lipoprotein cholesterol (HDL-C), lower apolipoprotein (apo)AI, and higher apoB than black boys. In boys of both races, increased body mass index was associated with increases in triglycerides, low-density lipoprotein cholesterol, apoB and decreases in HDL-C and apoAII. Within this framework, increased free testosterone was associated with increased apoB and decreased HDL-C and apoAI, whereas increased estradiol was associated with increased HDL-C and decreased triglycerides, low-density lipoprotein cholesterol, and apoB. CONCLUSION: Changes in sex steroid hormones have significant effects on changes in lipid parameters-increasing free testosterone levels has atherogenic effects and increasing estradiol has antiatherogenic effects.

Pubertal maturation in girls and the relationship to anthropometric changes: pathways through puberty.

OBJECTIVE: Patterns of pubertal maturation may have an impact on several risk factors associated with adult morbidity and mortality, such as obesity. We examined the relationship of the initial manifestation of puberty in girls with anthropometric measures, as well as age at menarche. METHODS: White females (n = 1166, ages 9 and 10 at intake) were followed with annual visits for 10 years. Physical examinations included height, weight, skinfold thicknesses, and pubertal maturation assessment. RESULTS: During the course of the study, 443 of 859 eligible females (51.6%) were observed to have asynchronous maturation in the development of puberty, that is, initial areolar/breast (thelarche pathway) or pubic hair (adrenarche pathway) development, without development of the other characteristic. Using a longitudinal regression model, significant interactions were noted between initial pubertal manifestation and years since onset of puberty on the following outcomes: sum of skinfolds thickness, percent body fat, waist-to-hip ratio, and body mass index (BMI). However, age of onset of pubertal maturation was the same in the 2 groups (10.7 years). Females in the thelarche pathway had earlier menarche (12.6 vs 13.1 years) as well as greater skinfolds, body fat, and BMI at the time of menarche. Females in the thelarche pathway also had greater body fat and BMI 1 year before puberty and throughout puberty compared with those in the adrenarche pathway. CONCLUSIONS: Females who enter puberty through the thelarche pathway, as compared with the adrenarche pathway, had greater sum of skinfold thicknesses, BMI, and percent body fat 1 year before the onset, as well as throughout, puberty. Because larger body composition and earlier age of menarche of females in the thelarche pathway parallel the epidemiologic profiles of women who are obese or at risk for obesity, these females may be at greater risk for adult obesity.