Age correction in cognitive, linguistic, and motor domains for infants born preterm: an analysis of the Bayley Scales of Infant and Toddler Development, Third Edition developmental patterns

Aim: To verify whether it is appropriate to use age correction for infants born preterm in all the developmental domains (cognitive, linguistic, and motor) considered by the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III). Method: Seventy-three infants born preterm (26–35wks) without major neurological sequelae and 67 infants born at term were assessed at 12 months (corrected age for infants born preterm). The performance of the infants born preterm was assessed with two different evaluations: scores based on uncorrected age and scores based on corrected age. Results: The developmental trends of infants born at term and infants born preterm differ across domains. Statistical analysis shows that age correction produces an overrated estimate of motor performance (12.5 points [95% confidence interval 9.05–16.01]) but not of cognitive performance. Interpretation: Given the broad use of the Bayley-III by psychologists and paediatricians, these results are important in the early diagnosis of developmental difficulties for children born preterm. Correction for gestational age should be applied for the cognitive domain only; whereas for the motor domain, chronological age should be used. No clear data emerged for language. What this paper adds: Age correction with Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III) for infants born preterm should be applied differently in cognitive, language, and motor domains. Using corrected age with Bayley-III, the motor skills are overrated. Correction for preterm births adequately measures cognitive skills. No clear indication emerged about language skills.