Table 1.
Demographic characteristics, gestational and birth factors, and cognitive test scores, early childhood longitudinal study-birth cohort (ECLS-B) study sample (N = 7,200)
| Mean or percenta | Standard deviation | |
|---|---|---|
| Male | 50% | |
| Child age (months), ECLS-B wave 2 | 24.39 | 1.16 |
| Child age (months), ECLS-B wave 3 | 52.54 | 4.10 |
| Ethnic origin | ||
| White, non-hispanic | 57% | |
| Black | 14% | |
| Hispanic | 22% | |
| Asian | 3% | |
| Native American | 0.4% | |
| Other | 4% | |
| Mother’s education, 24 month assessment | ||
| Less than 9th grade | 3% | |
| From 9th to 12th grade | 12% | |
| High school graduate | 31% | |
| Some training/college after high school | 27% | |
| Four year college degree and above | 26% | |
| Family income, 24 month assessment | ||
| Less than $10,000 | 9% | |
| Between $10,001 and $20,000 | 14% | |
| Between $20,001 and $40,000 | 27% | |
| Between $40,001 and $75,000 | 26% | |
| At or above $75,001 | 24% | |
| Mother’s education, 48 month assessment | ||
| Less than 9th grade | 3% | |
| From 9th to 12th grade | 10% | |
| High school graduate | 30% | |
| Some training/college after high school | 30% | |
| Four year college degree and above | 27% | |
| Family income, 48 month assessment | ||
| Less than $10,000 | 8% | |
| Between $10,001 and $20,000 | 12% | |
| Between $20,001 and $40,000 | 26% | |
| Between $40,001 and $75,000 | 25% | |
| At or above $75,001 | 28% | |
| Maternal age = 35 or older | 14% | |
| Marital status = unmarried, 48 month assessment | 32% | |
| Medical risk factor(s) | 0.18 | 0.52 |
| Behavioral risk factor(s) | 0.12 | 0.33 |
| Obstetric procedure(s) | 0.59 | 0.68 |
| Labor complication(s) | 0.36 | 0.67 |
| Multiple birth | 3% | |
| Gestation | ||
| Very preterm ≤32 weeks | 2% | |
| Moderately preterm 33–36 weeks | 9% | |
| Birthweight | ||
| Very low birthweight ≤1,500 g | 1% | |
| Moderately low birthweight 1,501–2,500 grams | 6% | |
| Congenital anomalyb | 5% | |
| Bayley mental score, 24 month assessment | 127.75 | 10.66 |
| Literacy score, 48 month assessment | 13.11 | 7.14 |
| Math score, 48 month assessment | 22.64 | 7.42 |
| Color knowledge score, 48 month assessment | 8.77 | 2.28 |
| Receptive vocabulary score, 48 month assessment | 8.60 | 1.92 |
| 48 Month assessment score | 53.12 | 16.00 |
The Bayley mental score was used as the cognitive score at 24 months; at 48 months, literacy, math, color knowledge, and receptive vocabulary scores were converted into z-scores and summed
Sample size rounded to nearest 50 in accordance with ECLS-B data confidentiality requirements (available at http://nces.ed.gov/ecls/birthdatainformation.asp)
aEstimates are weighted to take the complex sampling design into account
bAny congenital abnormality identified on the birth certificate