The Bayley Scales of Infant Development (BSID) are the most widely used assessments to identify children with developmental delay. Between 1993 and 2006, the BSID–Second Edition (BSID-II)1 was used; in 2006, a third edition (BSID-III)2 was published.
Rather than the 2-factor model of the BSID-II that described mental and psychomotor development, the BSID-III purports to assess 5 separate areas: cognition, language, motor, social-emotional, and adaptive. The aim of this study was to compare the BSID-II Mental and Motor scale scores and the BSID-III Motor, Cognitive, and Language scale scores in a cohort of very low-birth-weight preterm infants.