TABLE 2.

Characteristics of the Longitudinal Cohort (n = 2058)

WhitesBlacks
n1253805
Year of baseline examination1979 ± 51979 ± 5
Year of follow-up examination1985 ± 51985 ± 5
Initial age (y)7.2 ± 1.37.2 ± 1.4
Follow-up age (y)13.4 ± 1.713.4 ± 1.6
Menarcheal characteristics*
 Median age (y)12.612.3
 Before age 11.0 y (%)10%15%
 Before age 12.0 y (%)30%43%
 Before age 13.0 y (%)64%72%
 Postmenarcheal at follow-up (%)70%82%
Baseline characteristics
 Weight (kg)24.4 ± 7.224.9 ± 6.8
 Height (cm)121 ± 10123 ± 10
 BMI (kg/m2)16.4 ± 2.716.2 ± 2.4
 Triceps skinfold (mm)14 ± 512 ± 5
 Subscapular skinfold (mm)8 ± 57 ± 4
Age-specific scores
 Weight−0.1 ± 1.10.1 ± 1.0
 Height−0.2 ± 1.00.2 ± 0.9
 BMI0.1 ± 1.00.1 ± 1.0
  • * Estimates of median menarcheal age and proportions of girls who experienced menarche by specific ages are based on Kaplan-Meir (product-limit) estimates. The statistical significance of the racial difference in menarcheal age was assessed with the log-rank test.

  • A total of 1007 (of the 2058) girls had a subscapular skinfold thickness measurement at baseline.

  • P < .01.