Early Signs of Autism in Toddlers and Preschoolers

By FKT Editorial Team · 2026-05-14 · 1,957 words

As a parent, you know your child better than anyone. When something feels off — even if you can't put it into words — that feeling matters.

This article will help you understand which early signs of autism to watch for, how they appear at different ages, and what screening tools like the M-CHAT actually do. You'll also learn what your next steps look like if you have concerns.

This article supports the full Therapy for Autism: A Parent's Roadmap, which walks families through every stage of the autism journey — from first concerns to finding the right support.

Key Takeaways

Autism signs often appear before age 2, but many families don't get a diagnosis until age 4 or later.
Early screening is safe, simple, and free at most well-child visits.
The M-CHAT-R/F is the most widely used toddler autism screening tool in the U.S.
A failed screen does not mean your child has autism — it means follow-up is needed.
Early intervention, starting as young as 18 months, is linked to better long-term outcomes.

What Is Autism Spectrum Disorder?

Autism spectrum disorder (ASD) is a developmental condition. It affects how a person communicates, interacts with others, and processes the world around them.

The word "spectrum" matters. Autism looks different in every child. Some children speak in full sentences by age 3. Others may not use words at all. Some have intense sensory sensitivities. Others seem unbothered by the same input.

Because autism varies so much, it can be hard to spot early. Differences in development are easy to overlook — or explain away as "just a phase."

That's exactly why knowing the signs matters.

Why Early Detection Matters

Research consistently shows that early intervention leads to better outcomes for children with autism. The CDC reports that early intervention services — starting as young as 18 months — can make a meaningful difference in language, social skills, and daily functioning.

The American Academy of Pediatrics (AAP) recommends autism-specific screening at 18 and 24 months, on top of general developmental screening at every well-child visit. Their full guidance is at HealthyChildren.org.

But pediatricians only see your child for brief appointments. You spend every day with them. Your observations are a critical part of early detection.

For a deeper look at what the evaluation process looks like at different ages, see our sibling article Autism Diagnosis Age Timelines: What to Expect at Each Stage.

Developmental Red Flags by Age

Not every child develops at exactly the same pace. But certain skills typically appear by certain ages. When they don't, it's worth paying attention.

By 6 Months

Limited or no smiling at familiar faces
Few big expressions — joy, surprise, delight
Little back-and-forth eye contact with caregivers

By 12 Months

Not babbling or making sounds back at caregivers
No gestures — no pointing, waving, or reaching up to be held
Not responding to their name most of the time
Limited joint attention (not following your gaze or your pointing finger)

By 18 Months

No single words spoken meaningfully
Not pointing to show you things they find interesting
Loss of any language or social skills they previously had

By 24 Months

Fewer than 50 words
Not combining two words meaningfully (for example: "more juice" or "Daddy go")
Little interest in other children
Regression — losing skills they had before

Any loss of speech or social skills at any age is a red flag that warrants prompt evaluation. Don't wait for the next scheduled well-child visit if this happens. Call your pediatrician's office now.

Social and Communication Signs to Watch

Autism affects social communication in particular. Some signs are subtle, especially in toddlers who are still developing in many areas at once.

Watch for:

Limited eye contact. Your child may look away when you try to connect. They may not look at you when you call their name or make a funny face.

Reduced pointing. Most children start pointing to share interest by 12 months. A toddler who rarely points — or points only to get something, not to share excitement — may be showing an early sign.

Delayed or unusual speech. This includes repeating words out of context (called echolalia), speaking in a flat tone, or using phrases from TV shows instead of spontaneous conversation.

Difficulty with back-and-forth interaction. Conversations and play normally involve taking turns. A toddler who doesn't follow the back-and-forth of simple games — peek-a-boo, vocal exchanges — may be showing early social differences.

Limited pretend play. By age 2 to 3, most children are pretending to feed a doll or drive a toy car. Reduced or absent pretend play is a recognized early sign.

Behavior and Sensory Signs

Autism is also associated with repetitive behaviors and sensory differences. These can appear well before school age.

Repetitive behaviors include:

Lining up toys rather than playing with them in varied ways
Spinning wheels, fans, or other objects repeatedly
Repeating the same phrases or sounds over and over
Rigid routines — and intense distress when they change
Unusual hand movements, like flapping or finger-flickering

Sensory sensitivities include:

Covering ears often or becoming very upset by ordinary sounds
Refusing certain textures of food, clothing, or surfaces
Seeking intense sensory input — crashing into things, spinning, mouthing objects past the typical age
Being under-reactive — not noticing pain or temperature in expected ways

Sensory sensitivities and food selectivity often overlap. If you're navigating extreme picky eating alongside other autism signs, our sibling article Autism, Diet, and Sensory Food Selectivity has practical guidance for families.

Screening Tools: The M-CHAT and Beyond

The M-CHAT-R/F

The Modified Checklist for Autism in Toddlers, Revised with Follow-Up (M-CHAT-R/F) is the most commonly used autism screening tool for children between 16 and 30 months in the U.S.

It's a simple questionnaire — usually filled out by a parent in the waiting room before a well-child visit. The standard version has 20 yes/no questions. It asks things like:

Does your child look at things you point to?
Does your child play pretend?
Does your child use a pointer finger to show you things they find interesting?

Autism Speaks offers a free version of the M-CHAT-R online at autismspeaks.org. You can complete it at home and share results with your child's pediatrician.

A failed screen is not a diagnosis. It's a signal to take the next step — usually a more detailed follow-up conversation with a clinician, then a referral for a full evaluation. Research shows the M-CHAT is most accurate when the follow-up (F) portion is included if the initial screen is positive.

Other Commonly Used Tools

ASQ-3 (Ages and Stages Questionnaires) — A broader developmental screener that checks communication, fine motor, gross motor, problem-solving, and social skills. Many pediatricians use this at well-child visits before age 6.

ADOS-2 (Autism Diagnostic Observation Schedule) — A structured observation assessment conducted by a trained clinician. It's considered one of the gold standards for autism diagnosis.

ADI-R (Autism Diagnostic Interview, Revised) — A detailed interview with parents or caregivers covering your child's development from early childhood to the present.

The American Speech-Language-Hearing Association (ASHA) provides guidance on communication-specific assessments at asha.org.

What to Do If You Notice Red Flags

Noticing a sign does not mean your child has autism. And it doesn't mean anything is "wrong" with them. It means you're paying attention — and that's exactly what your child needs from you right now.

Here's a clear path forward:

1. Write things down and take videos. Specific examples give your pediatrician much more to work with than general worry. A 30-second video of a behavior can be worth more than a long explanation.

2. Bring it up at the next well-child visit — or call now. You don't have to wait. Most pediatricians welcome parent concerns between scheduled visits. Ask specifically: "Can we do an autism screening today?"

3. Request a referral if needed. If your pediatrician agrees that follow-up is warranted, ask for a referral to a developmental pediatrician, pediatric neurologist, or child psychologist.

4. Contact Early Intervention directly. Under federal law (IDEA Part C), children under 3 who show developmental delays qualify for free evaluations through their state's Early Intervention program. You don't need a diagnosis — or even a referral — to access this. The CDC maintains state-by-state information at cdc.gov/autism.

5. Start exploring your support options. If a diagnosis follows, the next step is finding the right therapists and services. Our full guide — Therapy for Autism: A Parent's Roadmap — covers ABA, speech therapy, occupational therapy, and more. For families beginning to think about school services, IEP Advocacy for Autism: A Parent's Playbook is a practical companion.

Frequently Asked Questions

What is the earliest age autism can be detected?

Research shows that reliable signs can sometimes be identified as early as 12 months. Experienced clinicians can diagnose autism in some children as young as 18 to 24 months. The CDC notes that a diagnosis made by a specialist at age 2 is considered reliable. That said, many children — especially girls and those with subtler profiles — are not identified until school age.

My child has some of these signs. Does that mean they have autism?

Not necessarily. Many signs overlap with other conditions — speech delays, sensory processing differences, hearing loss, or natural variation in development. A screening is the first step, followed by a full evaluation if needed. Only a qualified clinician can determine whether a child has autism.

My pediatrician says my child is fine, but I'm still worried. What should I do?

Get a second opinion. You are your child's best advocate. You can request a referral to a developmental specialist, contact Early Intervention directly (for children under 3), or ask your pediatrician to document their reasoning. Parental concern is a valid clinical data point — any good clinician will take it seriously.

Can girls show autism differently than boys?

Yes. Research increasingly shows that autistic girls often mask social difficulties more effectively than boys, making them harder to identify using tools calibrated on predominantly male study populations. Autistic girls may have better eye contact, more apparent social interest, and fewer obvious repetitive behaviors — while still struggling significantly beneath the surface. If you have a daughter and are concerned, be explicit about this with the evaluating clinician.

Is the M-CHAT available in languages other than English?

Yes. The M-CHAT-R has been validated in multiple languages. Autism Speaks (autismspeaks.org) and many state Early Intervention programs offer translated versions. Ask your pediatrician's office or your local Early Intervention coordinator.

Noticing signs is a first step — not a verdict. The earlier you act, the more options your child has.

FindKidTherapy is a directory of pediatric therapists across the United States. We connect families with speech-language pathologists, occupational therapists, behavioral specialists, and other providers. FindKidTherapy does not diagnose or provide therapy — but we can help you find the right professionals who do.

Start with the full Therapy for Autism: A Parent's Roadmap for a comprehensive look at how to support your child after concerns arise.

This article is for educational purposes only and is not medical advice. For diagnosis, treatment, or individualized recommendations, consult your pediatrician or a licensed therapist. FindKidTherapy is a directory of independent pediatric therapy providers; we are not a medical provider and do not provide therapy services.

Authored by the FKT Editorial Team.

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Part of our Therapy for Autism: A Parent's Roadmap guide.