Children Classified as Medium-Risk by the M-CHAT-R at Age Two Years Have an Increased Likelihood of Subtle but Widespread Developmental Challenges at Preschool Entry: Results From the French National Birth Cohort ELFE

BACKGROUND: The Modified Checklist for Autism in Toddlers - Revised (M-CHAT-R) is widely used for screening children at age 2 for autism spectrum disorders (ASD), but it also identifies children at risk for broader developmental challenges. We aimed to examine whether M-CHAT-R risk status at age 2 is associated with cognitive, behavioral, adaptive, and school-related outcomes at ages 3 to 4. METHODS: We used data from the French national birth Cohort ELFE, including children assessed with the M-CHAT-R at age 2. Children were classified as low or medium risk. Outcomes at ages 3-4 included general cognitive development (Child Development Inventory), non-verbal reasoning (Picture Similarities test), family and daily activities, school engagement and performance, attention regulation (teacher-rated ADHD symptoms), specific neurodevelopmental care and school-based assistance. Multivariate analyses used modified Poisson regression for binary outcomes and linear regression for continuous outcomes, adjusted for sociodemographic, child-related, and school-related factors. FINDINGS: 9,223 children were classified as low-risk and 1,248 children as medium-risk. Medium-risk children were more often boys and from socioeconomically disadvantaged families. At 3.5 years, medium-risk children had increased likelihood of developmental delay (16.6% vs. 6.1%, RR 2.2 after adjustment) and lower cognitive and language scores (up to -0.4 SD). Despite these differences, most children attended school, and their school life was similar to that of low-risk peers. INTERPRETATION: Children classified as medium-risk by the M-CHAT-R at age 2 have an increased likelihood of subtle but widespread developmental challenges at school entry. Strategies to improve access to neurodevelopmental care and school support could enhance outcomes for this group.