Autism disorder now affects 1 in 31 children in the United States, according to the latest 2025 data from the Centers for Disease Control and Prevention, making it more important than ever for parents to recognize early warning signs in toddlers.
Latest Research on Autism
A 2025 study from the University of Missouri's Thompson Center for Autism and Neurodevelopment found that signs of autism may appear as early as 9 months of age.
Researchers discovered that infants who were fussier, had difficulty adapting to new environments, struggled with sleep, and showed delays in reaching milestones were more likely to display early signs of autism by 12 months.
These findings suggest that paying attention to infant behavior earlier than expected could help identify children who need support, as per the University of Missouri.
Autism is typically diagnosed between ages 3 and 5, but the American Academy of Pediatrics (AAP) recommends that all children be screened for ASD during well-child visits at 18 and 24 months.
The CDC notes that ASD can sometimes be detected at 18 months or younger, and by age 2, a diagnosis by an experienced professional can be considered reliable.
Key Early Signs To Watch For
The signs of autism generally fall into two categories: differences in social communication and restrictive, repetitive behaviors.
Social Communication Signs
One of the most well-documented early signs is a delay in joint attention, the ability to share focus on an object or event with another person. According to Healthy Children, delays in joint attention are found in most children later diagnosed with autism.
Here is what parents should look for:
- By 12 months, most children look where a parent is pointing. A child showing signs of autism may not follow the gesture or may appear to ignore it entirely.
- By 15 months, most children point at objects they want. A child on the spectrum may instead take a parent's hand and lead it toward the object without making eye contact.
- By 18 months, most children point at things to share an interest. Children with autism may only point to request something, not to share an experience.
Other signs include not responding to their name, limited eye contact, lack of interest in games like peek-a-boo, and preferring to play alone.
Speech and Language Delays
Almost all children on the autism spectrum show some delays in nonverbal communication and spoken language, according to the AAP. A speech delay alone does not necessarily indicate autism. It becomes a concern when combined with other signs, such as limited gestures, little babbling by 12 months, or no single words by 16 months.
Repetitive Behaviors
Restrictive, repetitive behaviors are the second core feature of autism. These can include hand flapping, spinning, rocking, or unusual body postures.
Toddlers may also show intense fixation on specific objects or sensory experiences, such as watching water flow from a faucet or staring at spinning wheels, rather than playing with a toy in a typical way.
The Child Mind Institute notes that some repetitive behaviors are normal in young children whose nervous systems are still developing. Brief hand flapping during excitement does not automatically signal autism.
The key difference is frequency, intensity, and whether these behaviors appear alongside social communication challenges.
Why Early Detection Matters
Research consistently shows that the earlier a child receives intervention, the better the outcomes. A study highlighted by the Autism Research Institute found that toddlers who began intensive early intervention at 18 months showed significantly greater improvements than those who started at 27 months.
Early support can improve social skills, communication, and cognitive development during a critical window of brain growth, the Autism Research Institute said.
What Parents Should Do
Parents who notice any combination of these signs should talk to their child's pediatrician without delay. The AAP advises that children should be referred for intervention as soon as developmental delays are identified, rather than waiting for a formal diagnosis.
Screening tools such as the Modified Checklist for Autism in Toddlers are available during routine well-child visits. Acting early gives children the best chance at reaching their full potential.
