biostudies-literatureKoshy BDBT/Wellcome Trust India AllianceBill and Melinda Gates FoundationWellcome Truste082624https://www.ebi.ac.uk/biostudies/studies/S-EPMC11580237biostudies-literatureUnknown14(11)<h4>Objectives</h4>There is limited information about the stability and predictability of Bayley Scales of Infant and Toddler Development (BSID) assessing child development in low- and middle-income settings. The objective of the present study was to analyse stability and predictive validity of BSID using an existing birth cohort.<h4>Design</h4>Prospective birth cohort follow-up study.<h4>Setting and participants</h4>A community-based birth cohort of 251 newborns was recruited and followed-up in urban Vellore, South India, until 9 years of age. Using BSID-III, child development was measured at 6, 15, 24 and 36 months. Cognition was assessed using the Wechsler Preschool Primary Scales of Intelligence at 5 years, and the Malin's Intelligence Scale for Indian Children scale at 7 and 9 years oBMJ openStability and predictability of Bayley Scales of Infant and Toddler Development: evidence from a south Indian birth cohort prospective study.PMC11580237GR-681IA/CPHI/19/1/504611Koshy BScharf RKang GMohan VRMuliyil JSrinivasan MStrand TABeulah RJohn SfalseStability and predictability of Bayley Scales of Infant and Toddler Development: evidence from a south Indian birth cohort prospective study.<h4>Objectives</h4>There is limited information about the stability and predictability of Bayley Scales of Infant and Toddler Development (BSID) assessing child development in low- and middle-income settings. The objective of the present study was to analyse stability and predictive validity of BSID using an existing birth cohort.<h4>Design</h4>Prospective birth cohort follow-up study.<h4>Setting and participants</h4>A community-based birth cohort of 251 newborns was recruited and followed-up in urban Vellore, South India, until 9 years of age. Using BSID-III, child development was measured at 6, 15, 24 and 36 months. Cognition was assessed using the Wechsler Preschool Primary Scales of Intelligence at 5 years, and the Malin's Intelligence Scale for Indian Children scale at 7 and 9 years o2024-01-01T00:00:00Z2024 Nov2025-04-04T13:41:34.594Z2025-04-04T13:41:34.594ZS-EPMC115802373956695210.1136/bmjopen-2023-082624