Page 40 - Sample Moderate prematurity, socioeconomic status, and neurodevelopment in early childhood

Chapter 3
problems in MP children,13, 14 and three studies reported more problems within the hyperactivity spectrum such as attention problems.13, 14, 16 In addition, we found significantly more externalizing behaviour problems in MP children, in contrast to the findings of Van Baar et al. in 7-9-year-old Dutch children, and we also found more withdrawn behaviour problems.13 These differences may have gone unnoticed in those earlier studies because those had much smaller samples. However, the reported differences apparently do have clinical relevance, as odds ratios for MP children compared to term-born children were in a similar range as previously reported for very preterm and very low birth weight (VP/VLBW) children.26 Only one study reported no differences between children born at 34- 36 weeks and term-born children for externalizing, internalizing, aggressive, and anxious/depressed problems.12 This may be due to the restriction of that study to relatively healthy children from high-income families. The deleterious effects of preterm birth may be stronger among children born in poor families.25
Differences in behavioural and emotional problems by gender have previously been reported in studies on VP/VLBW children. Overall, VP/VLBW girls seem to have more internalizing problems, such as withdrawn behaviour, while VP/VLBW boys seem to be more susceptible to externalizing behaviour problems, especially in terms of attention problems.26-29 We found the same pattern of internalizing and externalizing problems in MP girls and boys but not in term-born children. Among term-born children, both internalizing and externalizing problems were more prevalent in boys than in girls. On most syndrome scales prevalence rates were also higher in term-born boys, except for anxious/depressed and sleep problems. To summarize, moderate preterm birth seems to have a greater effect on behavioural and emotional outcomes in girls than in boys. However, on total problems prevalence rates among girls did not differ much compared to rates among term-born boys. It still serves additional research why prematurity would affect behavioural and emotional outcomes more in girls than in boys. Currently, we have no real explanation for it. Differences in background characteristics could not explain these findings.
The important strengths of this study were its large community based sample, the collection of data in a similar way among MP and term-born children, and its high response rate. Moreover, this is the first study investigating the full range of behavioural and emotional problems in MP children just before they enter school. For measurement of behavioural and emotional problems the CBCL was used, which is a valid and widely used questionnaire.21 A large number of parents returned the CBCL questionnaires.
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