Case–control comparison of demographics, early development and educational needs
| Characteristic | Cases (n=29) | Controls (n=20) | P value |
| Age at testing in years, mean (SD) | 7.0 (0.5) | 7.0 (0.6) | 0.71 |
| Male sex, n (%) | 20 (69) | 12 (60) | 0.56 |
| National Readership Survey 16 social grade, n (%) | |||
| A (upper middle class) | 4 (14) | 3 (15) | |
| B (middle class) | 8 (28) | 6 (30) | |
| C1 (lower middle class) | 6 (21) | 4 (20) | |
| C2 (skilled working class) | 7 (24) | 5 (25) | |
| D (working class) | 3 (10) | 2 (10) | |
| E (casual worker or unemployed) | 1 (3) | 0 (0) | 0.98 |
| Gestational age in weeks, median (IQR) | 40.1 (39.3–40.7) | 39.9 (38–41) | 0.59 |
| Birth weight in g, median (IQR) | 3200 (3012–3680) | 3544 (3118–3997) | 0.10 |
| Age starting playgroup in months, median (IQR) | 24 (13–36) | 24 (12–36) | 0.67 |
| Age of independent walking in months, median (IQR) | 13 (12–15) | 12 (11–14) | 0.02 |
| Statement of special educational needs, n (%) | 1 (3) | 0 (0) | 1.0 |
| Extra classroom support, n (%) | 10 (34) | 1 (5) | 0.02 |
| Weight in kg, median (IQR) | 23.7 (21.4–27.25) | 24.6 (22.9–26.7) | 0.65 |
| Weight centile, median (IQR) | 48.0 (31.9–84.3) | 61.05 (47.33–80.83) | 0.64 |
| Height in cm, median (IQR) | 121 (117–126) | 125 (124–130) | 0.03 |
| Height centile, median (IQR) | 43.8 (17.5–75) | 71.1 (50.5–87.2) | 0.02 |
| Body mass index, median (IQR) | 15.9 (14.9–17.9) | 15.5 (14.9–16.1) | 0.21 |
| Head circumference in cm, median (IQR) | 52.4 (51.5–53.7) | 52.6 (51.8–53.1) | 0.73 |