Early Signs of Autism in Babies, Toddlers, and Young Children: A Parent’s Guide
Written by Behavior Frontiers as Part of Their Bright Futures Series
Understanding your child’s development is one of the most important parts of parenting. While every child grows at their own unique pace, some early differences in communication, behavior, and social interaction may suggest signs of autism spectrum disorder (ASD).* Recognizing these autism signs early can help you take the next step with confidence, clarity, and support.
In this guide, we’ll explore the early signs of autism in infants, signs of autism in 18 months and older, and how to know if your child may benefit from an evaluation or early intervention care.
What Is Autism?
Autism spectrum disorder (ASD) is a neurodevelopmental difference that shapes how a person communicates, interacts socially, and experiences the world around them. It exists on a spectrum, meaning characteristics can vary widely from child to child. Some children may show early signs in infancy, while others may display them later in toddlerhood or go undetected.
Understanding the early signs of autism can help families feel more informed and empowered, especially during those early years of rapid development.
Why Early Detection and Intervention Matters
Recognizing the early signs of autism can help you take meaningful steps to support your child’s development. During the first few years of life, the brain is especially adaptable–a concept known as “neuroplasticity”–which means it’s a powerful window of opportunity to build communication, social, and learning skills.
In fact, research shows that children who begin high-quality Applied Behavior Analysis, or ABA Therapy (the only research-backed autism treatment method) before age 3 often make more significant and lasting progress. Early support can boost your child’s ability to connect with others, express themselves, and gain independence over time.
Identifying autism early allows families to understand their child’s needs and begin personalized care that builds on their unique strengths. Whether through center-based ABA therapy or in-home support, starting early can help your child thrive in ways that feel natural, playful, and deeply rewarding.
Importantly, it’s also important to remember that growth is always possible. Children, teens, and adults with autism continue to learn, connect, and thrive at every stage with the right support. So, whether you're finding yourself searching “is my toddler autistic,” just starting to notice differences in your young child, seeing new behaviors in your 8-year-old, or have had questions for a while, the best time to take the next step is now–toward a future where your child feels understood, supported, and empowered.
How Early Can You See Signs of Autism?
Some early signs of autism may be observable in infants around 6 months of age, though this also varies from child to child. While professionals can often make a reliable diagnosis by age 2, autism signs at 18 months and even earlier are not uncommon.
Typical Developmental Milestones (6 Months – 4 Years)
The CDC (cdc.gov) outlines typical developmental milestones for children ages 6 months through 4 years as listed below. These represent general patterns of growth in areas like social interaction, language, and play.
Although it’s common for children to grow at their own pace–and not every child will follow these timelines exactly–knowing what’s typical can help you recognize when it might be time to check in with your pediatrician.
By 6 Months
Responds to their own name
Reacts to other people’s emotions and often seems happy
Likes to play with others, especially parents or caregivers
Copies sounds
Knows familiar faces and may recognize strangers
Enjoys looking at self in the mirror
By 12 Months, or 1 Year Old
Uses simple gestures like waving or shaking head “no” or waving “bye-bye”
Says “mama,” “dada,” or other simple expressions like “uh-oh!”
Enjoys playing back and forth games like Peek-a-boo
Responds to simple spoken requests
Points to show interest
Shows preference for favorite people or toys
Puts out arm or leg to help with dressing
By 18 Months
Plays simple pretend (e.g., feeding a doll)
Points to share something interesting
Enjoys handing things to others as play
Says several single words
Begins joint attention (looking back and forth between caregiver and object)
Shows affection to familiar people
By 24 Months, or 2 Years Old
Says simple two- to four-word sentences
Follows simple directions
Gets excited around other children
Points to things or pictures of things when they are named
Shows increasing independence and some defiant behavior (does what they are told not to)
By 36 Months, or 3 Years Old
Carries on short conversations (2–3 sentences)
Shows affection for friends without prompting
Plays pretend with dolls, animals, and people
Copies adults and peers
By 48 Months, or 4 Years Old
Tells stories
Prefers playing with others over playing alone
Cooperates with other children in group settings
Potential Signs of Autism to Look For
While it’s important to remember that individual development varies widely from child to child, certain patterns may point to autism spectrum disorder (ASD). These signs may appear as early as 6–12 months and often become clearer between ages 1–3.
Common Early Signs of Autism:
Limited or no eye contact
Does not respond to name by 12 months
Few or no gestures like pointing or waving
Rarely imitates sounds, expressions, or play
No words by 16 months or no meaningful phrases by 24 months
Repeats words or phrases without clear context (echolalia)
Prefers playing alone or lining up toys rather than engaging in pretend play
Strong resistance to changes in routine
Repetitive movements, such as flapping, rocking, or spinning
Hyper- or hypo-sensitivity to sounds, lights, textures, or smells
Having one or a few of these signs doesn't automatically mean your child has autism–but if you're noticing several signs consistently, especially past the age when typical milestones are reached, it may be a good idea to check in with your pediatrician.
When or How Early Can Autism Be Diagnosed?
Autism can often be reliably diagnosed by age 2, but early signs of autism in infants may be observable as early as 6–12 months. The American Academy of Pediatrics recommends autism screenings at 18 and 24 months during well-child visits.
These screenings are quick and non-invasive, and they help identify whether your child may benefit from early autism care, such as ABA therapy.
What Should I Do If I Notice Signs of Autism in My Child?
If you're starting to see developmental differences or early signs of autism:
Talk to your pediatrician – Share your observations and ask about an autism screening or evaluation. A developmental specialist can provide more insight.
Track developmental milestones – Use the CDC’s milestone tracker or printables.
Explore early autism intervention treatment options, such as center-based ABA therapy with Behavior Frontiers. ABA therapy is the only research backed method that has been shown to support the development of key comprehensive skills in toddlers with autism, such as communication, social, play, daily living (such as toilet training and eating), emotional regulation, and more.
You’re Not Alone: Support from Behavior Frontiers
If you have questions about your child’s development, you’re not alone–and you don’t have to navigate this journey by yourself. While a formal diagnosis is the first step in accessing autism-specific services, Behavior Frontiers is here when you’re ready to take the next one.
At Behavior Frontiers, we offer personalized, data-driven ABA programs to support each child’s unique strengths, interests, and goals–in center-based programs for children under 6, and in-home for children and young adults under age 25.
“He loves it. He plays with toys now. He’s around kids... The best part is he has started talking again. Just yesterday, he said his name back to me. All of this might sound small–but it’s a huge step forward in getting to communicate with my son again.” (Review from Louise via Google)
“When you have an ABA team like Behavior Frontiers, you can be assured you are not alone in this journey. Highly recommend!” (Review from Amy via Google)
“This team collaborates with our school team for continuous shared knowledge… We are blessed to have such an awesome team…” (Review from Gigi via Google)
Your Child’s Journey Starts Here
If you've been wondering “What are the early signs of autism?” or “What should I do next if my toddler is showing symptoms of autism?”, your first step is to talk to your pediatrician about a developmental screening or evaluation. Once you have a diagnosis (offered through Behavior Frontiers in select regions, contact us for more info), Behavior Frontiers is here to help your child thrive through compassionate, evidence-based ABA Therapy.
Ready to enroll your child in comprehensive ABA therapy with Behavior Frontiers?
Call us at 888-922-2843 or fill out the short form below and we’ll reach out within one business day to walk you through the next steps.