The VP/VLBW cohort and the reference samples had similar background characteristics except for maternal educational level, which was lower for VP/VLBW children (p<0.05; table 1).
Table 1Background characteristics of the very preterm or very low birthweight children and children from the Dutch general population*
VP/VLBW children had higher mean scores on CBCL total problems, on internalising and externalising problems, and on all syndrome scales (p<0.05), except for sex problems and anxious/depressed behaviour (table 2). Repetition of the analyses with adjustment for background characteristics did not affect differences in any important way (data not shown). The Mann–Whitney U test mostly confirmed the results of the t test (table 2).
Table 2Mean Child Behavior Checklist scores of very preterm or very low birth weight children and children from the Dutch general population (aged 5 years)
Table 3 shows that the proportion of children scoring in the clinical range of CBCL total problems was 13.2% among VP/VLBW children versus 8.7% among those from the general population (odds ratio (OR) 1.60, 95% confidence interval (CI) 1.18 to 2.17); for the somewhat lower borderline cut‐off criterion, these figures were 22.1% v 15.0% (OR 1.61, 95% CI 1.26 to 2.05), respectively. The proportion of VP/VLBW children scoring in the clinical range was higher also for externalising problems but not for internalising problems. Differences in proportions regarding separate syndrome scales reflected those for mean scores, although some differences did not reach statistical significance, considering the relatively small proportions of children with a clinical score.
Table 3Prevalence rates of scores in the clinical range on Child Behavior Checklist problems scales for very preterm or very low birthweight children and children from the Dutch general population (aged 5 years)
Standardised differences (effect sizes) ranged from 0.08 to 0.44 (fig 1). Values for four CBCL syndromes and for externalising and total problems were >0.2, which Cohen24
designates as small effects, which were largest for attention and social problems. Differences were much larger for VP/VLBW children in whom the paediatrician assessed developmental problems than for the other children. Again, excesses in problems were largest for attention and social problems, 0.70 and 0.67, respectively, which Cohen24
designates as medium (ie >0.50) effects. Regarding the group with paediatrician‐assessed problems, the excess of problems was larger if the paediatricians were certain of the existence of developmental problems than if they were uncertain and first needed additional investigation, for all CBCL syndromes (data not shown).
Figure 1Standardised differences in mean Child Behavior Checklist scores of very preterm or very low birthweight (VP/VLBW) children and those of children in the general population (that form the zero x axis level of the figure), overall and separately (more ...)
Whether the children were only very preterm, only VLBW or both had no statistically significant effect on differences in behavioural and emotional problems, and neither had the 5‐min Apgar score. However, children who had needed artificial ventilation for at least 1 week in the neonatal period (n
66) had significantly higher scores on social (p<0.001) and attention problems (p
0.020). Children with grade 3 or 4 intraventricular haemorrhage (n
19) had higher scores on somatic complaints (p
0.027), and children who received corticosteroids (n
14) had higher mean scores for total problems (p
0.028), and social (p<0.001), thought (p
0.011) and attention problems (p
0.014). In all cases, differences between the VP/VLBW children without additional perinatal problems and children from the general population sample remained statistically significant. Moreover, differences regarding receipt of artificial ventilation, presence of intraventricular haemorrhage and receipt of corticosteroids were much smaller than those regarding paediatrician‐assessed problems at 5 years (fig 1).
Finally, the excess of problems among VP/VLBW children differed somewhat by sex (table 4). Among VP/VLBW boys, this excess was slightly larger for behavioural (externalising) type problems, but sex‐related differences were statistically significant regarding only social and attention problems. Among girls, the excess of problems was somewhat larger for emotional (internalising) type problems, but this sex‐related difference was statistically significant regarding only the withdrawn behaviour on the CBCL syndrome scale.
Table 4Mean Child Behavior Checklist scores of very preterm or very low birthweight children and of children from the general Dutch population, by sex (age 5 years)