Early Neurodevelopmental Milestones in Children With Autism Spectrum Disorder: A Retrospective Observational Study

Introduction Early diagnosis and intervention in autism spectrum disorder (ASD) are crucial for improving cognitive, social, and adaptive outcomes. ASD is characterized by deficits in social communication and interaction, alongside restricted and repetitive behaviors. Although diagnosis typically occurs around age three, developmental concerns often emerge within the first year, particularly in language, social engagement, and adaptive functioning. Early identification of these markers allows timely referral, assessment, and intervention. This study aimed to characterize early neurodevelopmental milestones in preschool children with ASD, compare milestone acquisition with normative expectations using Haizea-Llevant charts, and evaluate associations with cognitive and adaptive functioning using the Griffiths Mental Development Scales-Extended Revised (GMDS-ER). Materials and methods A retrospective observational study included 127 children with ASD followed at a tertiary hospital Neurodevelopment Unit. Data from medical records included demographics, prenatal and family history, comorbidities, age at referral and diagnosis, and early clinical signs. Six developmental milestones were analyzed: social smile, sitting without support, walking, first words, first phrases, and urinary daytime sphincter control. Delays were defined as acquisition at or above the 95th percentile of the Haizea-Llevant chart or absence of the milestone. Language regression, defined as loss of at least five previously acquired words for ≥3 months, was recorded. Cognitive and adaptive functioning were assessed using GMDS-ER, including global development quotient (GDQ) and subscales for personal/social, hearing/language, locomotor, hand-eye coordination, and performance. Statistical comparisons between normative and delayed milestone acquisition were performed. Results Of the 127 children, 85.8% were male, with a mean age at diagnosis of 34±10 months. Language delay was the most frequent reason for referral; 11% had experienced regression. Social smile was delayed in 20.5%, sitting in 2.5%, walking in 38.6%, first words in 62.6%, first phrases in 96.8%, and daytime sphincter control in 85.2%. GMDS-ER assessments in 62.2% of children showed a mean GDQ of 61.8±12.7. Delayed sphincter control was associated with lower GDQ (60.2 vs. 76.2, p=0.002), personal/social (56.7 vs. 70, p<0.01), hearing/language (42 vs. 51.7, p=0.048), and performance scores (69.3 vs. 78, p=0.011). Delayed social smile correlated with lower personal/social scores (51.1 vs. 60, p=0.03). Delays in first words (56.7 vs. 64, p=0.014) and phrases (58 vs. 80.5, p=0.023) were linked to reduced personal/social outcomes. Delayed walking was associated with lower performance scores (62.8 vs. 72.8, p=0.025). Discussion and conclusion Motor milestones in the first year, except walking, were generally achieved on time. Delayed walking, language acquisition, and daytime sphincter control were strongly associated with lower cognitive, social, and adaptive outcomes. Delayed social smile was associated with poorer personal/social functioning. Careful monitoring of early milestones, particularly social, language, and adaptive skills, can facilitate early ASD identification and guide timely, individualized interventions that may improve long-term outcomes.