Are there critical periods for brain growth in children born preterm?
BACKGROUND
Children born very preterm who attend mainstream schools have a high prevalence of minor motor, behavioural, and learning disorders. These appear to be associated with reduced postnatal growth, particularly of the head. It is unclear when this poor growth occurs and whether growth restriction during different periods has different effects on later function.


OBJECTIVE
To identify periods during early development, in children born preterm, when impaired head growth may influence minor motor and cognitive function.


METHODS
A geographically defined cohort of 194 infants born in Merseyside during 1980-81 and weighing less than 1500 g.


METHODS
Measurements of head circumference (occipitofrontal circumference (OFC)) were available at birth, hospital discharge, 4 years, and 15 years of age. Assessments of intelligence (intelligence quotient (IQ)) and minor motor impairment (test of motor impairment (TOMI)) were made at 8 years of age. Clinical, social, and demographic variables were obtained from the clinical record and maternal interviews.


RESULTS
IQ correlated significantly with OFC at 4 and 15 years of age after correction for growth restriction at birth (intrauterine growth restriction (IUGR)) and social class. TOMI scores correlated significantly with OFC at all four times, but especially with OFC at discharge and with change in OFC between birth and discharge. They were not affected by correction for social class or IUGR.


CONCLUSIONS
Although both IQ and minor motor impairments correlate strongly with each other at school age in very low birthweight children, the factors determining them and their timing of operation are different. Interventions designed to improve IQ in this population would need to reduce IUGR and improve later childhood growth. Those aimed to improve motor ability need to be targeted more at brain protection during the neonatal period.
Cooke
R W I
RW
School of Reproductive and Developmental Medicine, University of Liverpool, UK. mc19@liv.ac.uk
D001921:Brain / Q000254:growth & development*; D002508:Cephalometry; D002657:Child Development; D002675:Child, Preschool; D003072:Cognition Disorders / Q000209:etiology; D015331:Cohort Studies; D003423:Critical Period, Psychological; D002658:Developmental Disabilities / Q000209:etiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000254:growth & development*; D019102:Infant, Very Low Birth Weight / Q000254:growth & development; D007360:Intelligence; D008297:Male; D019957:Motor Skills Disorders / Q000209:etiology; D009778:Occipital Lobe / Q000254:growth & development; D011597:Psychomotor Performance; D012923:Social Class