Farin Soleimani - MD, Pediatrician, Research Professor, Pediatric Neurorehabilitation Research Center, Speech & Language Pathology Department, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
Adis Kraskian - PhD, Assistant Professor, Department of Psychology, Karaj Branch, Islamic Azad University, Karaj, Iran.
Mehdi Noroozi - PhD, Assistant Professor of Epidemiology, Substance Abuse and Dependence Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
Ali khakshour - Clinical Research Development Unit of Akbar Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
Nadia Azari - MD, Pediatrician, Pediatric Neurorehabilitation Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.

Rehabilitation Sciences, Tehran, Iran. AbstractBackground: There is a wide variety of sociocultural and environmental background characteristics in different geographical places of Iran. The aim of this study was to investigate the rates of developmental delay in Tehran in comparison to the norm of Iran, using the Bayley III measure.Methods: This cross sectional study was a part of a national study conducted in Iran, between ۲۰۱۴ and ۲۰۱۶. During the study period, five hundred fifty Persian speaking children in Tehran were included. The sampling was in proportion to the population of children covered in each region. First, the differences between the scaled scores, based on the norms of Tehran and Iran were calculated and then, a one sample Multivariate Analysis of Variance (MANOVA) was used, which showed a significant difference between the scaled scores. Next, we used a univariate analysis to find which scales these significant differences were generated from. Finally, the rate of children with low scores (<-۱SD, and <-۲ SD) were compared by means of the McNemar analyses.Results: The numbers of male participants were ۳۱۰ (۵۴.۵%). The mothers in the sample of Tehran had higher educational levels in comparison to those in the sample of Iran (P= ۰.۰۰۱). Considering Iran’s norm compared to Tehran’s norm leads to significantly fewer rates of delay, on cognition scale (<-۱SD; ۱۱.۶% to ۱۹.۸%) and fine motor scale (<-۱SD; ۱۵.۱% to ۲۱.۱%)(<-۲SD; ۱.۶% to ۳.۳%) respectively (p <۰.۰۱). The differences in estimation rate were somewhat age-dependent. The greatest difference between the norm of Tehran and Iran was in the age group of “۲۵ months ۱۶ days to ۴۲ months ۱۵ days”.Conclusion: In some developmental domains, the norm of Iran in comparison to that of Tehran indicates a lower rate of children with developmental delay.

Bayley Scales of Infant and Toddler Development, testing norms, Child development, Infants, toddlers