A large longitudinal study from Sweden analyzed autism spectrum disorder (ASD) diagnoses in 2.7 million people born between 1985 and 2022, followed from birth to age 37.[1] Autism was diagnosed in 78,522 individuals, which represents 2.8% of the monitored group, at an average age of diagnosis of 14.3 years.[1] The prevalence of ASD has increased over the past three decades, with the traditional ratio of boys to girls around 4:1.[1] However, the study showed a decrease in this ratio over time and with increasing age of diagnosis, with a significant catch-up effect in adolescent girls.[1] Diagnoses were most common in boys aged 10-14 and in girls aged 15-19.[1][8] By adulthood, the ratio of boys to girls has evened out so much that it is no longer distinguishable.[1] Researchers emphasize the need to investigate why girls are diagnosed later than boys.[1]