Re-evaluating preterm infants with the Bayley-III: patterns and predictors of change.

This study investigates the Third Edition of the Bayley Scales of Infant and Toddler Development (Bayley-III) and (1) mean difference scores, (2) test-retest correlation coefficients, (3) changes in rates of delay and classification from "delayed" to "not delayed," and (4) infant birth, neonatal and sociodemographic predictors of change in scores from the first to second year of life among 131 preterm infants. Cognitive, Receptive Language and Fine Motor Subscale scores decrease and mean Gross Motor Subscale scores remain consistent from the first to second year of life. Bayley-III test-retest reliability ranged from small/fair to moderate from 8 to 20 months corrected age. Classification of delay is not stable over the first two years of life. One in 6 infants' Language Index scores changed from a classification of not delayed at 8 months to delayed at 20 months. One in 10 infants' Gross Motor Subscale scores changed from a classification of delayed at 8 months to not delayed at 20 months. Small for gestational age status predicts improved to nearly consistent Bayley Language Index and Receptive Subscale scores. Public insurance and history of sepsis predict decline in Bayley Language Index and Receptive Subscale scores from 8 to 20 months. Lower gestational age, race, and history of necrotizing enterocolitis and/or intestinal perforation also predict decline in Bayley Cognitive Index from 8 to 20 months. Predictors of decline in performance confirm known neonatal risk factors, are consistent with emerging evidence of detrimental immune related processes, and highlight the importance of inclusion of sociodemographic variables in understanding development in preterm infants.