Table 1.
Mean Levels of Various Characteristics in the Study Sample
| Whites | Blacks | |
| N | 771 | 408 |
| Number of examinations | 4.6 ± 1* | 5.0 ± 1* |
| 2–4 examinations | 45% | 31% |
| ≥ 5 examinations | 55% | 69% |
| Initial examination | ||
| Year | 1975 ± 3 | 1973 ± 3 |
| Age (y) | 8.7 ± 2 | 8.9 ± 2 |
| Weight (kg) | 29.2 ± 10* | 30.6 ± 11* |
| Weight-for-Age Za | -0.2 ± 1* | 0 ± 1* |
| Height (cm) | 130 ± 15* | 133 ± 15* |
| Height-for-Age Za | -0.2 ± 1** | 0.1 ± 1** |
| BMI (kg/m2) | 16.8 ± 3 | 16.9 ± 3 |
| BMI-for Age Za | -0.06 ± 1 | -0.05 ± 1 |
| Triceps skinfold thickness (mm) | 14 ± 5** | 12 ± 5** |
| Menarcheal age (y)b | 12.9 ± 1 | 12.8 ± 1 |
| Menarche before age 12 yb | 25% | 30% |
| Final Examination | ||
| Age (y) | 26 ± 4 | 26 ± 4 |
| Weight (kg) | 66.7 ± 17** | 73.5 ± 22** |
| Height (cm) | 163 ± 6 | 163 ± 7 |
| BMI (kg/m2) | 25.1 ± 6** | 27.7 ± 8** |
| Triceps skinfold thickness (mm) | 24 ± 10 | 25 ± 12 |
| Subscapular skinfold (mm) | 21 ± 11** | 25 ± 13** |
a Z-scores express levels relative to those among children in national studies conducted between 1963 and 1994 (see Methods); b Based on data from the first examination at which menarche was first reported. The mean age of girls at this examination was 16 y. H0: Black vs. white difference equals 0 as assessed by a t-test: *p < 0.05; **p < 0.001