Neurodevelopmental outcome of Italian preterm children at 1 year of corrected age by Bayley-III scales: An assessment using local norms

Background Premature birth is often associated with neurodevelopmental difficulties throughout childhood. In the first three years of life, the Bayley Scales of Infant and Toddler Development-Third Edition (Bayley-III) constitute one of the most used tools for assessing child development. Since Bayley-III original norms are based on United States (US) population, it remains uncertain whether their use in other countries (e.g., European) is appropriate. Aims This research aimed to examine neurodevelopment of preterm infants and full-term infants, using Bayley-III US norms in comparison to Italian (IT) norms. Patterns of developmental outcomes for both infant groups were also explored. Methods 104 preterm and 58 full-term infants were included in the study. Bayley-III was used for neurodevelopmental assessment at 1 year of corrected age, considering both IT and US norms for scores computation. Results Comparing scores obtained with IT vs US norms, differences in means were all significant across five subscales (p < 0.05 at least) for preterm infants, whereas for full-term peers significant differences were found only for Receptive Language and Fine Motor subscales (p < 0.001). Effect size (η²) ranged from 0.22 to 0.94. Within each group, significant discrepancies across subscales were found. Moreover, Italian preterm infants had significantly lower performances than full-term peers, excepting for Expressive Language and Gross Motor subscales. Conclusions As regards to Italian 1-year children, our study seems to provide evidence for the tendency of Bayley-III US norms to overestimate development compared to IT norms. These findings emphasize the need to early detect children at risk for developmental delay and to plan early intervention.