Developmental Milestones for Children With Down Syndrome.

Objectives: The American Academy of Pediatrics recommends that children and adolescents with Down syndrome receive anticipatory guidance regarding development and behavior. However, few tools provide specific guidance on developmental norms for children with Down syndrome. Our objective was to estimate age ranges at which children and adolescents with Down syndrome achieve developmental milestones to facilitate developmental screening by pediatric practitioners.

Methods: We used standardized questionnaires to obtain information from clinicians and caregivers of children with Down syndrome who received care at the Boston Children's Hospital Down Syndrome Program between March 2018 and March 2023. Data included information from 2599 visits for 842 individuals with Down syndrome ages 2 months to 24 years. We used mixed-effects logistic regressions to predict the probability of achieving 25 specific developmental milestones with 15%, 30%, 45%, 60%, 75%, and 90% probability as a function of age. We further stratified results by individuals' sex.

Results: We present age norms for our study's population of people with Down syndrome for key milestones in academic, adaptive, language, and motor domains by calculating the ages at which milestone achievement was 75% probable. We then compare these norms to published norms for the general population.

Conclusions: This study provides clinicians and families with age-based norms for achievement of key developmental milestones for children and adolescents with Down syndrome.