Table 1.
Characteristics of the sample by predictor domains and their correlations with IQ at 4 years of age
| Correlation with IQ at 4 years of age | |||
|---|---|---|---|
|
Indicators of the sample N = 114 |
Descriptive statistics of variables | correlation coefficient (r) | significance (p) |
| Demographic variables of parents | |||
| Maternal education (primary, %) | 14.91 | 0.492 | < 0.001 |
| Family wealth (below average, %) | 6.14 | 0.392 | < 0.001 |
| Ethnicity (Roma, %) | 11.40 | -0.315 | 0.001 |
| Perinatal variables at birth | |||
| Birth weight (mean ± SD) | 1310.08 (545.72) | 0.402 | < 0.001 |
| Gestational age (mean ± SD) | 30.00 (3.85) | 0.295 | 0.001 |
| Sex (Male, %) | 43.85 | -0.044 | 0.639 |
| Twin pregnancy (yes, %) | 41.20 | 0.164 | 0.081 |
| Apgar at 1 min. (mean ± SD) | 6.97 (1.74) | 0.245 | 0.014 |
| Apgar at 5 min. (mean ± SD) | 8.24 (1.02) | 0.257 | 0.010 |
| Smoking during pregnancy (yes, %) | 20.17 | -0.407 | < 0.001 |
| Neonatal variables after birth | |||
| Retinopathy of prematurity (yes, %) | 15.70 | -0.335 | < 0.001 |
| Intraventricular haemorrhage (yes, %) | 12.28 | -0.242 | 0.010 |
| Bronchopulmonary dysplasia (yes, %) | 14.91 | -0.408 | < 0.001 |
| Developmental characteristics at 2 years of age | |||
| BSID-III Raw scores | |||
| Cognitive skills (mean ± SD) | 7.99 (2.76) | 0.623 | < 0.001 |
| Receptive comm. (mean ± SD) | 8.51 (2.43) | 0.592 | < 0.001 |
| Expressive comm. (mean ± SD) | 7.28 (2.67) | 0.342 | < 0.001 |
| Fine motor skills (mean ± SD) | 8.50 (2.57) | 0.621 | < 0.001 |
| Gross motor skills (mean ± SD) | 7.82 (2.47) | 0.495 | < 0.001 |
| BSID-III Composite scores | |||
| Cognitive skills (mean ± SD) | 90.17 (13.99) | 0.613 | < 0.001 |
| Language skills (mean ± SD) | 88.18 (13.07) | 0.535 | < 0.001 |
| Motor skills (mean ± SD) | 89.07 (13.77) | 0.632 | < 0.001 |
| Mean performance | |||
| ∑Cog.-Lang.-Mot.a (mean ± SD) | 89.14 (11.85) | 0.683 | < 0.001 |
BSID-Bayley Scales of Infant and Todler Development
aThe mean of Cognitive composite score, Language composite score, and Motor composite scores
Coding of categorical data: Ethnicity: Roma = 1, Hungarian = 0; Sex: Male = 1, Female = 0; Smoking during pregnancy: Yes = 1, No = 0; Neonatal diagnosis of Retinopathy: Yes = 1, No = 0; Neonatal diagnosis of Bronchopulmonary dysplasia: Yes = 1, No = 0; Neonatal diagnosis of Intraventricular haemorrhage: Yes = 1, No = 0