Table 1.
Baseline Characteristics and Age at Menarche by Race
| Baseline Characteristic | Mean (SD) |
P Value | |
|---|---|---|---|
| Black Girls Aged 9-10 y (n=983) | White Girls Aged 9-10 y (n=907) | ||
| Annual household income, No. (%), $ | |||
| <20 000 | 443 (45.1) | 141 (15.6) | <.001 |
| 20 000-50 000 | 393 (40.0) | 446 (49.2) | |
| >50 000 | 147 (15.0) | 320 (35.3) | |
| Parental education, No. (%) | |||
| ≤HS | 293 (29.8) | 164 (18.1) | <.001 |
| Post-HS/some college | 478 (48.6) | 277 (30.5) | |
| ≥4 y of college | 212 (21.6) | 466 (51.4) | |
| Study center, No. (%) | |||
| Berkeley, California | 369 (37.5) | 351 (38.7) | .86 |
| Cincinnati, Ohio | 339 (34.5) | 304 (33.5) | |
| Washington, DC | 275 (28.0) | 252 (27.8) | |
| Height, cm | 143.0 (7.8) | 139.5 (7.0) | <.001 |
| Weight, kg | 39.5 (10.7) | 35.1 (8.5) | <.001 |
| Body mass indexa | 19.1 (4.1) | 17.9 (3.3) | <.001 |
| Waist circumference, cmb | 66.5 (9.4) | 63.3 (8.1) | <.001 |
| Hip circumference, cmb | 83.2 (10.4) | 79.1 (8.5) | <.001 |
| Waist to hip ratiob | 0.80 (0.045) | 0.80 (0.044) | .94 |
| Body fat % | 21.5 (8.9) | 20.6 (7.3) | .01 |
| Dietary intake, total kcal | 1973 (457) | 1810 (333) | .12 |
| Total fat intake, % kcal | 36.1 (3.3) | 33.0 (3.8) | <.001 |
| Fiber intake, g/d | 11.3 (3.2) | 11.9 (3.1) | .054 |
| Television/video watching, h/wk | 38.3 (14.1) | 20.1 (12.0) | <.001 |
| Age at menarche, y | 12.0 (1.2) | 12.7 (1.2) | <.001 |
Abbreviation: HS, high school.
a
Calculated as weight in kilograms divided by height in meters squared.
b
First measurement was at the second study visit (age, 10-11 years).