Every child develops at their own pace, and occasional variation in milestones is completely normal. But when a parent notices that their child is consistently not meeting developmental milestones — or when a behavior pattern seems different from what they observe in other children — it is natural to wonder whether something more is going on.
Autism spectrum disorder (ASD) affects approximately 1 in 36 children in the United States, according to the most recent data from the CDC. It can be reliably identified as early as 18 months, yet the average age of diagnosis in the U.S. remains around four years old. That gap represents a critical window of time during which early intervention could be making a difference.
Why early identification matters
The brain is most adaptable during the first few years of life — a period neuroscientists refer to as heightened neuroplasticity. During this window, the brain is forming connections at an extraordinary rate, and therapeutic interventions can have an outsized impact on how those connections develop. Children who begin intensive behavioral therapy before age five consistently show the greatest improvements in communication, social skills, and adaptive behavior.
Early identification does not mean labeling a child prematurely or making assumptions about their future. It means giving that child access to support during the period when support is most effective. A diagnosis is not a sentence — it is a key that unlocks services, funding, and interventions that can genuinely change a child's developmental trajectory.
Signs to watch for by age
Autism presents differently in every child, and no single sign is definitive on its own. The following are patterns that, taken together, may indicate that a professional evaluation is warranted.
By 6 to 12 months, most typically developing infants are making eye contact, responding to their name, smiling back at caregivers, and beginning to babble. Children who will later be diagnosed with autism may show reduced eye contact, limited social smiling, little interest in interactive games like peek-a-boo, and delayed or absent babbling.
By 12 to 18 months, most children are pointing at objects to share interest (not just to request), using a few single words, and engaging in simple pretend play. Warning signs at this age include not pointing or waving, not responding consistently to their name, loss of previously acquired words or social skills, and a strong preference for solitary play.
By 18 to 24 months, children are typically combining two words, imitating others, showing interest in peers, and engaging in more complex pretend play. Signs that may warrant evaluation include not using two-word phrases, not imitating actions or sounds, limited interest in other children, repetitive movements with objects (lining up, spinning), and strong reactions to changes in routine or sensory input.
After age two, additional signs may become more apparent: difficulty with back-and-forth conversation, taking language very literally, intense or narrow interests, difficulty understanding other people's feelings, and challenges with transitions or changes in routine. Some children, particularly girls, may mask or compensate for social difficulties, which can delay identification.
The difference between a sign and a diagnosis
It is important to emphasize that observing one or even several of these signs does not mean your child has autism. Many of these behaviors occur in typically developing children as well. What matters is the pattern — when multiple signs are present together, when they persist over time, and when they are significantly different from what is observed in same-age peers.
Only a qualified professional can diagnose autism spectrum disorder. A diagnosis typically involves a comprehensive evaluation that includes parent interviews, direct observation using standardized tools (such as the ADOS-2), developmental history, and assessment of the child's current skills. This evaluation is conducted by a developmental pediatrician, child psychologist, or neurologist.
What to do if you have concerns
If you are concerned about your child's development, the most important thing you can do is act on that concern rather than waiting. Parents are remarkably accurate at identifying when something is different about their child's development — research shows that parental concern is one of the strongest early indicators.
Start by talking to your pediatrician. Describe the specific behaviors you are observing and when they occur. Ask whether a developmental screening or referral for a comprehensive evaluation is appropriate. If your pediatrician suggests a "wait and see" approach and you are not comfortable with that, you have every right to seek a second opinion or request a referral directly.
You can also take a validated screening tool at home to help guide the conversation. The M-CHAT-R (Modified Checklist for Autism in Toddlers, Revised) is a free, evidence-based screener designed for children ages 16 to 30 months. It takes less than five minutes to complete and can help identify whether a formal evaluation is recommended.
While waiting for an evaluation, you do not need to wait to seek support. Early intervention services are available in every state for children under age three through the Individuals with Disabilities Education Act (IDEA) Part C program. In Florida, this is managed through the Early Steps program. These services are available regardless of whether your child has a formal diagnosis.
The path forward
Receiving an autism diagnosis for your child can bring a mix of emotions — relief at having an explanation, grief for expectations that may need to be adjusted, and uncertainty about what comes next. All of these feelings are valid, and they can coexist.
What comes next is action. With the right support — early, intensive, and individualized — children with autism can make extraordinary progress. The children in our programs who started early and received consistent, high-quality ABA therapy have gone on to develop meaningful communication, build friendships, succeed in school, and gain independence in ways their families once worried might not be possible.
If you have concerns about your child's development, do not wait. Take our free M-CHAT screener, talk to your pediatrician, or contact us for a no-cost consultation. The earlier your child gets support, the more effective that support will be.