Growth impairment in the very preterm and cognitive and motor performance at 7 years

Abstract

Background: Infants born of low birth weight often have poor subsequent growth (especially if they were born very preterm), which has been shown to relate to later motor and cognitive development.

Aims: To assess a cohort of preterm infants at the age of 7 years for growth, motor, and cognitive measures, and investigate the effects of growth impairment on school performance.

Methods: A cohort of 280 children born before 32 completed weeks of gestation were tested, together with 210 term controls.

Results: Preterm children were significantly lighter and shorter than term controls and had smaller heads and lower body mass index (BMI). Median centiles for weight, height, head circumference, and BMI were 25, 25, 9, and 50 for boys and 50, 25, 9, and 50 for girls compared with 50, 50, 50, and 75 for controls. They performed significantly less well on all tests with a mean score of 91 (9.2) on the Developmental Test of Visual-Motor Integration, 89 (14.5) on the Wechsler-III IQ test, and 30.7% scoring at or below the 5th centile on the Movement Assessment Battery for Children. In boys, short stature and small heads were the best predictors of poor performance; in girls, a small head alone was a predictor for poor motor and cognitive performance.

Conclusion: Poor postnatal growth in preterm infants, especially of the head, is associated with increased levels of motor and cognitive impairment at 7 years of age. This growth restriction appears to occur largely in the postnatal rather than antenatal period and may be amenable to intervention and subsequent improvement in outcome.

Figure 1

Graph of SDS for head circumference at birth (b-OFC-SDS) against change in SDS between birth and seven years (d-OFC-SDS), showing that those with the greatest loss in relative head circumference were not those most growth restricted at birth.

Figure 2

Graph of SDS for head circumference at birth (b-OFC-SDS) against SDS for head circumference at seven years (OFC-SDS), showing that most of the preterm infants now growth restricted were not so at birth.