| Time point | Subject | Potential score | Mean, SD (Range) | |
|---|---|---|---|---|
| Unstandardized | Standardized | |||
| Birth | 4023 | 0–13 | 10.4 ± 1.1 (5–13) | 79.7 ± 8.6 (38.5–100) |
| 3 months | 3120 | 0–9 | 7.3 ± 1.5 (2–9) | 81.5 ± 17.0 (22.2–100) |
| 6 months | 3987 | 0–10 | 5.4 ± 1.3 (2–10) | 53.9 ± 12.9 (20.0–100) |
| 9 months | 3543 | 0–15 | 8.5 ± 1.3 (5–14) | 56.5 ± 8.9 (33.3–93.3) |
| 12 months | 3355 | 0–13 | 7.4 ± 1.2 (4–12) | 56.7 ± 9.6 (30.8–92.3) |