Page 25 - Sample Moderate prematurity, socioeconomic status, and neurodevelopment in early childhood

social skills. The risk of delay in problem-solving skills was significantly associated with decreasing SES but not with decreasing GA.
Our finding that moderate prematurity and low SES were separate risk factors
for developmental delay supports the findings of two recent studies. A study
of Woythaler et al. showed that medical factors, including moderate preterm
birth at 34 to 37 weeks’ gestation, as well as sociodemographic factors affected 2 neurodevelopmental outcomes at 24 months of age.5 Quigley et al. reported that
both moderate prematurity and low maternal educational level were associated
with poorer educational achievement at age five.10 Furthermore, in these studies socioeconomic factors had a greater share in poor developmental or educational
outcomes than GA. This seems to be the case in our study too, though mainly for problem-solving skills.
Because of the higher rate of prematurity among low SES families, the association of moderate prematurity with developmental delay could have been a reflection of low SES effects. This was hypothesized while many socioeconomically-graded risk factors have been identified for preterm delivery, such as obesity, hypertension, smoking and stress. However, we found that SES neither weakened nor strengthened the association between moderate prematurity and developmental delay. Therefore, our results support the hypothesis that GA itself is linked to developmental delay.
Developmental problems are rather common in early preterm-born children, as reported in several studies.6,17-19 The risk increases with decreasing GA: it has been suggested that e.g. intelligence quotient decreases 1.7 to 2.5 points per week below 32 weeks of gestation.19 MP children miss out on four to eight weeks of brain growth and development in utero, which may also put them at risk of developmental problems. Moderate prematurity has been associated with a smaller, and more specific array of developmental problems than early prematurity. Impairments include impaired fine motor skills, handwriting, coordination, and verbal fluency.6,7,9,10 Higher rates of white matter injury in early preterm-born children explain a part of this difference, but the developmental stage of the central nervous system at birth might be even more important.17,20 Evidence from neuroscience shows that microstructural and neural connectivity processes are disturbed due to prematurity and this disturbance may result in atypical differentiation of neuronal pathways.21 Especially the limbic system and the cerebellum undergo structural changes after 32 weeks of gestation, and missing four to eight weeks of brain growth and development in utero may manifest itself later in difficulties
Developmental outcomes: risks multiply
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