A longitudinal study of the cognitive and social development of preterm infants

Abstract

Technological advances are enabling increasingly premature infants to survive and it is this particularly vulnerable population that are exposed, often for prolonged periods of time, to the hazards of the Neonatal Intensive Care Unit environment which can have adverse developmental consequences.
Premature infants have been shown to have difficulties with cognitive/developmental outcomes, social interaction, security of attachment and are frequently perceived as having a more difficult temperament than their term counterparts.
The aim of this study was to address these issues by comparing a group of premature infants (gestational age between 28-33 weeks) of low risk status with a matched group of term infants at 6 and 12 months of age (corrected age for the preterm group) to confirm if there were differences.
Cognitive/developmental outcomes were assessed by the Bayley Scales of Infant Development, Second Edition (BSID, II) using the mental developmental index. Nursing Child Assessment Teaching Scale (NCATS, Barnard, 1978), was used for measures of social interaction. The Attachment Behaviour Q-sort (Version 3.0; Waters and Deane, 1985) was used to assess security of attachment and the Infant Characteristics Questionnaire (ICQ, Bates, Freeland & Lounsbury, 1979) was used to measure perceived difficult temperament.
The results indicated that Bayley MDI scores of the preterm group were significantly lower than those of the term group at both 6 and 12 months, however, both groups fell within the accepted norms.
There was no significant difference in security of attachment, nor on any of the maternal social interaction measures, nor on perceived difficult temperament between the groups. However, preterm infants obtained lower mean scores on infant social interaction measures.
Bayley scores were positively associated with cognitive growth fostering for both groups. There was a marginal relationship, for the preterm group, between scores on the MI)I and attachment security, but there was no association between attachment security and measures of social interaction for the preterm group and attachment security was negatively associated with maternal sensitivity for terms.
There was an association, for the term infants only, between difficult temperament ratings and Bayley scores and between temperament and attachment for the preterm infants which appeared to reflect differences in maternal caregiving.
These finding should be interpreted with the caveat that because of the large number of correlational analyses, there may be a significant element of false positive observations within the results. The few differences found between pre-term and term infants, however, may be partially due to the fact that the cohort of preterm infants were of low risk status and sample sizes were small but it may also be an indication of recent improvements in the NICU environment.