The registry-based prevalence of ASD at age 8 increased markedly ranging from 2.1‰ in 2003 to 13.5‰ in 2024. In 2024, the prevalence reached 21.1‰ among boys. The increase was predominantly driven by ASD without ID, which accounted for nearly 70% of recent cases. For recent cases the median age at diagnosis was 4 years. Over 20% had co-occurring attention deficit hyperactivity disorder, while sleep and eating disorders were also frequent. Schooling and care arrangements differed substantially according to the presence of ID.