Table 1 Characteristics of U.S. singleton term births born in 2001, Early Childhood Longitudinal Study-Birth Cohort (ECLS-B) study sample
| Â | % of Sample Births | Birth Weight (grams) | |
|---|---|---|---|
mean | sd | ||
TOTAL | 100% | 3423.6 | 477.7 |
Child Sex (%) | |||
  Male | 51% | 3485.9 | 478.7 |
  Female | 49% | 3358.2 | 467.9 |
Parity (%) | |||
  First child | 41% | 3378.6 | 473.8 |
  Not first child | 59% | 3454.3 | 478.0 |
Gestation (weeks) | 39.3 | Â | 1.5 |
Adequacy of prenatal care (Kessner Index) (%) | |||
  Adequate | 78% | 3443.7 | 468.6 |
  Intermediate | 17% | 3355.4 | 498.0 |
  Inadequate | 5% | 3335.9 | 463.8 |
Mother's education (%) | |||
   < 12 years | 20% | 3361.5 | 471.5 |
  12 years | 31% | 3390.0 | 482.6 |
  13—15 years | 22% | 3460.8 | 467.0 |
   > 15 years | 26% | 3485.9 | 470.8 |
  unknown | 1% | 3328.4 | 539.0 |
Mother's race/ethnicity | |||
  White, non-Hispanic | 61% | 3476.2 | 406.1 |
  Black, non-Hispanic | 14% | 3348.1 | 500.3 |
  Hispanic, any race | 21% | 3409.6 | 414.4 |
  AAPIa | 3% | 3272.0 | 997.0 |
  American Indian/Alaskan Native | 1% | 3446.3 | 1490.8 |
Fathers 's race/ethnicity | |||
  White, non-Hispanic | 55% | 3479.9 | 409.0 |
  Black, non-Hispanic | 10% | 3315.4 | 478.2 |
  Hispanic, any race | 19% | 3408.3 | 404.7 |
  AAPIa | 3% | 3270.1 | 1048.3 |
  American Indian/Alaskan Native | 1% | 3440.8 | 1363.7 |
  Not stated | 12% | 3318.5 | 515.5 |
Mother's marital status | |||
  Married | 69% | 3459.8 | 464.4 |
  Not Married | 31% | 3344.1 | 497.3 |
Mother's age | |||
Mean (years) | 27.3 | Â | 6.1 |
  < 20 yrs (%) | 11% | 3318.6 | 507.5 |
  20—24 | 26% | 3355.0 | 457.0 |
  25—29 | 27% | 3452.5 | 454.9 |
  30—34 | 23% | 3481.3 | 485.2 |
  35—39 | 11% | 3471.3 | 490.1 |
  > 39 | 2% | 3515.1 | 516.7 |
Father's age | |||
Mean (years) | 38.3 | Â | 22.9 |
  < 45 yrs (%) | 86% | 3439.0 | 471.0 |
  ≥ 45 | 2% | 3401.1 | 498.2 |
  Not stated | 12% | 3313.1 | 508.54 |
Urbanicity (%) | |||
  Rural | 14% | 3405.2 | 476.2 |
  Urban | 86% | 3426.6 | 477.9 |
Region (%) | |||
  Northeast | 17% | 3432.2 | 448.5 |
  Midwest | 23% | 3461.2 | 483.5 |
  South | 37% | 3397.5 | 466.2 |
  West | 23% | 3421.8 | 506.9 |
Smoked during pregnancy (%) | |||
  Yes | 11% | 3257.4 | 452.5 |
  No | 75% | 3449.0 | 468.2 |
  Unknown | 14% | 3412.6 | 520.2 |
Poverty | |||
  < 185% Poverty | 47% | 3358.0 | 482.0 |
  =  > 185% | 53% | 3481.1 | 466.5 |