Background characteristics of the 11-year-old children (n=170) born at very low gestational age (<32 weeks) or with a very low birth weight (≤1500 g)
| Characteristics | Study children, n=170 | Children who withdrew, n=49 | P value |
| Gestational age, mean (SD) (minimum, maximum), weeks | 29.1 (2.7) (23.0, 35.9) | 29.0 (2.7) (23.7, 34.1) | 0.9 |
| Birth weight, mean (SD) (minimum, maximum), g | 1134.4 (315.3) (400.0, 2120.0) | 1184.6 (374.5) (565.0, 1970.0) | 0.3 |
| Small for gestational age (<−2 SD), n (%) | 56 (32.9) | 11 (22.5) | 0.2 |
| Male, n (%) | 94 (55.3) | 30 (61.2) | 0.5 |
| Caesarean section, n (%) | 101 (59.4) | 32 (65.3) | 0.5 |
| Bronchopulmonary dysplasia, n (%) | 22 (12.9) | 7 (14.3) | 0.8 |
| Operated necrotising enterocolitis, n (%) | 7 (4.2) | 3/48 (6.3) | 0.7 |
| Sepsis, n (%) | 30 (17.7) | 7 (14.3) | 0.6 |
| Laser-treated retinopathy of prematurity, n (%) | 4 (2.4) | 3/47 (6.4) | 0.2 |
| Brain MRI at term age, n (%)* | 0.9 | ||
| Normal findings | 96/165 (58.2) | 29/48 (60.4) | |
| Minor pathologies | 27/165 (16.4) | 7/48 (14.6) | |
| Major pathologies | 42/165 (25.5) | 12/48 (25.0) | |
| Mother’s education, n (%) | 0.04 | ||
| ≤12 years | 61/168 (36.3) | 24/45 (53.3) | |
| >12 years | 107/168 (63.7) | 21/45 (46.7) | |
| Father’s education, n (%) | 0.4 | ||
| ≤12 years | 110/166 (66.3) | 32/44 (72.7) | |
| >12 years | 56/166 (33.7) | 12/44 (27.3) |
*The specific MRI protocol and details about the classification of the findings have been previously described by Setänen et al.40