Pierce K, et al. - In this prospective cohort study involving 1,269 toddlers, researchers investigated at what point diagnosis of autism spectrum disorder (ASD) becomes stable in a large cohort of toddlers starting at 12 months of age. They then compared this stability with that of toddlers with other disorders, such as developmental delay. The results indicate that at the age of 14 months, a diagnosis of ASD becomes stable, and compared to other classifications of diagnosis, including language or developmental delay is more stable overall. If a toddler is diagnosed with ASD, odds are low that he or she will test at typical levels at 3 years of age. Testing the impact of ASD therapy at a very early age may be possible with this finding.