Table II.
Distribution of children in each category of confounders included in the final model across the three nicotine exposure groups (n=5,119). Values are either proportions or means (SD).
| Prenatal nicotine exposure | ||||
|---|---|---|---|---|
| None | Low | High | Overall | |
| Sex | ||||
| Male | 48.5 | 52.3 | 48.7 | 48.8 |
| Female | 51.5 | 47.7 | 51.3 | 51.2 |
| Ethnicity* | ||||
| White | 96.9 | 94.1 | 94.9 | 96.4 |
| Non-white | 3.1 | 5.9 | 5.1 | 3.6 |
| Type of school child attends | ||||
| Primary | 91.9 | 92.9 | 97.7 | 92.2 |
| Private | 5.9 | 4.8 | 1.6 | 5.6 |
| Other | 2.2 | 2.3 | 0.8 | 2.2 |
| Literacy based interaction* | ||||
| High | 47.1 | 42.8 | 35.8 | 46.3 |
| Moderate | 45.9 | 47.1 | 54.1 | 46.2 |
| Low | 7.1 | 10.1 | 10.1 | 7.5 |
| Verbal based interaction | ||||
| High | 65.3 | 67.1 | 66.1 | 65.6 |
| Moderate | 30.2 | 27.4 | 27.4 | 29.8 |
| Low | 4.5 | 5.1 | 6.5 | 4.6 |
| ADHD | ||||
| Yes | 1.4 | 2.4 | 1.6 | 1.5 |
| Gestational age | ||||
| ≥37wks | 95.4 | 94.9 | 95.3 | 95.3 |
| ≤36wks | 4.6 | 5.2 | 4.7 | 4.8 |
| Marital status* | ||||
| Married | 87 | 70.1 | 61.3 | 84.1 |
| Social class - Maternal* | ||||
| Manual | 11.9 | 23.9 | 37.5 | 14.1 |
| Non-manual | 88.1 | 76.1 | 62.5 | 85.9 |
| Antenatal class attendance* | 68.2 | 66.9 | 51 | 67.4 |
| Alcohol consumption* | ||||
| Never | 45.1 | 36.2 | 32.9 | 43.6 |
| <1 glass PWK | 41 | 40 | 38.4 | 40.7 |
| 1+ glasses PWK | 12.8 | 20.2 | 22.6 | 14.1 |
| 1+ glasses PDAY | 1.1 | 3.6 | 6.2 | 1.6 |
| Resuscitation | 8.3 | 7.3 | 6 | 8 |
| Birth weight gm* | 3467.1 (507.4) | 3343.5 (533.6) | 3294.4 (511.3) | 3443.2 (516.7) |
| Mother’s age at delivery* | 29.7 (4.3) | 28.0 (4.9) | 27.4 (5.1) | 29.4 (4.5) |
| Phonology | 20.9 (9.2) | 20.6 (8.8) | 19.2 (9.3) | 20.8 (9.1) |
| Total IQ* | 107.4 (15.0) | 104.4 (14.3) | 99.9 (13.8) | 106.7 (15.0) |
*
Indicates χ2 p value < .05 from univariable analyses of each covariate and prenatal nicotine exposure outcome.