Table 1.
Selected sample characteristics for mothers and infants participating in the New Hampshire Birth Cohort Study (n = 214).
| Maternal Variables | Mean (range) or % |
|---|---|
| Maternal Age, years | 31.5 (18.6–44.6) |
| <20 | 1.4% |
| 20–29 | 33.2% |
| 30–35 | 45.3% |
| >35 | 20.1% |
| Education Level* | |
| <11th grade | 2.0% |
| High school graduate/ GED | 8.2% |
| Junior college, some college, technical school | 17.9% |
| College graduate | 44.4% |
| Postgraduate schooling | 27.5% |
| Relationship status* | |
| Single | 10.7% |
| Married | 85.7% |
| Separated or divorced | 3.6% |
| Smoking during pregnancy* | |
| Yes | 5.6% |
| No | 87.0% |
| Secondhand smoke exposure* | |
| Yes | 4.7% |
| No | 87.3% |
| Parity* | |
| Nulliparous | 44.4% |
| Multiparous | 54.2% |
| Infant Variables | |
| Infant Sex | |
| Male | 45.7% |
| Female | 54.3% |
| Birth Weight, grams* | 3456.9 (1380.0–5318.0) |
| Gestational age, weeks* | 39.6 (31.1–44.9) |
| Childcare Setting at 4 months | |
| Home | 64.5% |
| Daycare | 35.5% |
| Type of feeding at 4 months | |
| Breast-fed only | 42.1% |
| Formula-fed only | 9.3% |
| Combination | 48.6% |
*
Sum of subjects less than total sample size due to missing values. Eighteen subjects were missing education level and relationship status, sixteen were missing smoking and secondhand smoke exposure, three were missing parity, four were missing birth weight and twenty-nine were missing gestational age, for which missing values were imputed using the average of observed values.