Cognitive Development of Very Low Birth Weight Children from Infancy to Pre-school Age
Background:
The survival of preterm born infants has increased but the prevalence of long–term morbidities has still remained high. Preterm born children are at an increased risk for various developmental impairments including both severe neurological deficits as well as deficits in cognitive development. According to the literature the developmental outcome perspective differs between countries, centers, and eras. Definitions of preterm infant vary between studies, and the follow–up has been carried out with diverse methods making the comparison less reliable. It is essential to offer parents up–to–date information about the outcome of preterm infants born in the same area. A centralized follow–up of children at risk makes it possible to monitor the consequences of changes in the treatment practices of hospitals on developmental outcome.
Subjects:
This thesis is part of a larger regional, prospective multidisciplinary follow–up project entitled “Development and Functioning of Very Low Birth Weight Infants from Infancy to School Age” (PIeniPAinoisten RIskilasten käyttäytyminen ja toimintakyky imeväisiästä kouluikään, PIPARI). The thesis consists of four original studies that present data of very low birth weight (VLBW) infants born between 2001 and 2006, who are followed up from the neonatal period until the age of five years.
Methods:
The main outcome measure was cognitive development and secondary outcomes were significant neurological deficits (cerebral palsy, CP, deafness, and blindness). In Study I, the early crying and fussing behavior of preterm infants was studied using parental diaries, and the relation of crying behavior and cognitive and motor development at the age of two years was assessed. In Study II, the developmental outcome (cognitive, CP, deafness, and blindness) at the age of two years was studied in relation to demographic, antenatal, neonatal, and brain imaging data. Development was studied in relationship to a full–term born control group born in the same hospital. In Study III, the stability of cognitive development was studied in VLBW and full–term groups by comparing the outcomes at the ages of two and five years. Finally, in Study IV the pre–cursors of reading skills (phonological processing, rapid automatized naming, and letter knowledge) were assessed for VLBW and full–term children at the age of five years. Pre–reading skills were studied in relation to demographic, antenatal, neonatal, and brain imaging data.
Results:
The main findings of the thesis were that VLBW infants who fussed or cried more in the infancy were not at greater risk for problems in their cognitive development. However, crying was associated with poorer motor development. The developmental outcome of the present population was better that has been reported earlier and this improvement covered also cognitive development. However, the difference to full–term born peers was still significant. Major brain pathology and intestinal perforation were independent significant risk factors for adverse outcome, also when several individual risk factors were controlled for. Cognitive development at the age of two years was strongly related with development at the age of five years, stressing the importance of the early assessment, and the possibility for early interventions. Finally, VLBW children had poorer pre–reading skills compared with their full–term born peers, but the IQ was an important mediator even when children with mental retardation were excluded from the analysis.