Sample characteristics
| Characteristic | Boys | Girls |
| Number of subjects | 1439 | 1409 |
| Age (y)—mean (SD) (range) | 9.14 (2.02) (5.37–13.61) | 9.03 (2.01) (5.03–13.57) |
| Standard deviation height score—mean (SD) | 0.27 (0.99) | 0.22 (1.04) |
| Birth weight (kg)—mean (SD) | 3.44 (0.56) | 3.32 (0.57) |
| Number of children who had repeated a grade | 88 | 45 |
| Maternal education (%)1-150 | ||
| ⩽ Year 10 | 27 | 28 |
| Year 11/12 | 31 | 31 |
| Trade apprenticeship/technical diploma | 16 | 15 |
| Tertiary/postgraduate degree | 21 | 20 |
| Paternal education (%)1-150 | ||
| ⩽ Year 10 | 20 | 19 |
| Year 11/12 | 17 | 18 |
| Trade apprenticeship/technical diploma | 30 | 32 |
| Tertiary/postgraduate degree | 22 | 20 |
| Responding parent's country of birth (%)1-150 | ||
| Australia/New Zealand | 72 | 72 |
| Other English speaking | 7 | 7 |
| South East Asian | 2 | 2 |
| Eastern European | 2 | 2 |
| Mediterranean | 3 | 4 |
↵1-150 Percentages do not add up to 100 due to missing data.