| Summary: | There has been considerable debate among cognitive psychologists and epidemiologists
regarding which determinants of children’s intelligence are most important. Factors
such as children’s diet, maternal stress and social support are important for general
health and wellbeing, but have received little research attention in longitudinal studies
involving cognitive outcomes. Few studies have examined the determinants of
intelligence in children born small-for-gestational age (SGA) at term even though these
children may be particularly vulnerable to poorer postnatal environments. The aim of
this study was to identify factors associated with cognitive ability in middle childhood
in New Zealand (NZ) European children and children born SGA.
The present research was conducted as part of the Auckland Birthweight Collaborative
(ABC) study. Approximately half of the children in this study were born SGA
(birthweight<10th percentile) and half were born appropriate-for-gestational age
(AGA=birthweight>10th percentile). Information was collected from mothers and
children on pregnancy, obstetric, socio-demographic, postnatal and dietary factors when
the children were born (n=871), at one year (n=744), 3.5 years (n=550), and 7 years of
age (n=591). Cognitive ability was assessed at 7 years using the Wechsler Intelligence
Scale for Children – Third Edition. For the total sample, the analyses utilised weighting
to allow for the disproportionate sampling of children born SGA.
Results showed that SGA and AGA children did not differ in intelligence at 7 years.
Factors associated with intelligence included maternal pregnancy factors (e.g.
hypertension), socio-demographic factors (e.g. paternal education), and postnatal factors
(e.g. maternal social support). In general, the effects of environmental factors did not
differ significantly for SGA children compared with AGA children.
A number of dietary factors were also found to be significantly and positively
associated with intelligence measures including higher intakes of breads and cereals and
weekly fish consumption. In contrast, daily margarine consumption was associated
with significantly lower intelligence scores, particularly in SGA children, and this is the
first study to report this association.
iii
Dietary and “environmental” factors were stronger predictors of children’s intelligence
in middle childhood than “biological” factors, such as infant’s birthweight.
Importantly, most of the factors associated with intelligence that were identified in this
study are potentially modifiable. Further research is needed to examine whether these
factors continue to be associated with cognitive ability in later childhood.
|
|---|
