Table 1.

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