Early Signs of Autism in Babies & Toddlers: What Parents Should Know

TL;DR: Early signs of autism can appear as young as 6 to 12 months and become more noticeable by 18 to 24 months. Key signs include limited eye contact, not responding to their name, delayed speech, not pointing or waving, and unusual play patterns. The average age of diagnosis is still 4 years — but signs can be detected much earlier. Early intervention (especially before age 3) leads to significantly better outcomes. If you notice signs, don’t wait — talk to your pediatrician and request an evaluation. Trusting your instincts as a parent is one of the most important things you can do for your child.

As a parent, you notice things. Maybe your baby doesn’t look at you the way your friend’s baby looks at her mom. Maybe your toddler isn’t pointing at airplanes or waving bye-bye. Maybe your preschooler lines up toys instead of playing with them, or melts down at every small change in routine.

You might be wondering if what you’re seeing is within the range of “normal” — or if it could be a sign of autism spectrum disorder (ASD). This article walks you through the earliest signs of autism at every age, what’s not necessarily a sign, and exactly what to do if you have concerns.

The most important thing to know: Noticing these signs and seeking evaluation is an act of love, not a reason for guilt. You’re not overreacting. You’re being a good parent.

Why Early Detection Matters

The brain develops more rapidly in the first five years of life than at any other time. During this window, neural connections are forming at an extraordinary rate — up to 1 million new connections per second. This plasticity means that early intervention can literally reshape your child’s developmental trajectory.

Research consistently shows:

• Children who begin therapy before age 3 show the greatest improvements in language, social skills, and adaptive behavior
• A landmark study (Dawson et al., 2010) found that toddlers who received early intervention showed significant gains in IQ and adaptive behavior, with some no longer meeting diagnostic criteria for autism after 2 years
• The American Academy of Pediatrics recommends autism screening at 18 and 24 months — because early identification leads to earlier intervention

Yet the average age of autism diagnosis in the United States is still around 4 years. That’s a gap of 2 or more years between when signs first appear and when children get help. Closing that gap starts with parents like you knowing what to look for.

Signs in Babies (6–12 Months)

At this age, the signs are subtle. Many parents don’t notice anything unusual, and that’s OK — early signs are easy to miss. But looking back, some parents report noticing these patterns:

Social and Communication Signs

• Limited eye contact — doesn’t look at you as often as you’d expect during feeding, play, or conversation
• Doesn’t respond to their name — by 9 months, most babies turn when you say their name. Consistently not responding may be a sign.
• Doesn’t follow your gaze — when you look at something, your baby doesn’t follow your eyes to see what you’re looking at (called “joint attention”)
• Limited babbling — by 9–12 months, most babies babble with consonant sounds (ba-ba, da-da, ma-ma). Less babbling may signal a communication difference.
• Doesn’t reach to be picked up — many babies with autism don’t raise their arms to be held

Behavioral Signs

• Unusually stiff or floppy body — differences in muscle tone can sometimes be an early indicator
• Limited facial expressions — doesn’t smile back at you by 6 months or show a range of emotions by 9 months
• No gestures — doesn’t wave, point, or shake head by 12 months

Important context: Many babies develop on different timelines. A single sign from this list doesn’t mean your child has autism. It’s the pattern across multiple areas that warrants attention.

Concerned about your baby’s development? Talk to your pediatrician. You can also take our screening quiz to explore your options.

Signs in Toddlers (12–24 Months)

This is the age when signs typically become more noticeable. Many parents describe a growing sense that “something is different” during the toddler years.

Communication Signs

• No single words by 16 months — most toddlers say at least a few words by this age
• No two-word phrases by 24 months — “more milk,” “daddy go,” “my ball” — if your child isn’t combining words by age 2, it’s worth investigating
• Loss of previously acquired words or skills — this regression occurs in about 25–30% of children later diagnosed with autism and is one of the most concerning signs
• Doesn’t point to show you things — by 12–14 months, most toddlers point at objects they find interesting to share the experience with you. This is different from pointing to request something.

Social Signs

• Doesn’t bring things to show you — toddlers typically share discoveries (“Look at this rock!”). A child who doesn’t seek to share experiences may have difficulty with joint attention.
• Doesn’t engage in pretend play — by 18 months, most toddlers begin pretending (feeding a doll, talking on a toy phone). Absence of pretend play by 24 months is a notable sign.
• Limited interest in other children — doesn’t watch, approach, or try to play with peers
• Doesn’t imitate — doesn’t copy your actions, sounds, or expressions

Behavioral Signs

• Lines up toys or objects — arranging items in rows rather than playing with them functionally
• Repetitive movements — hand-flapping, spinning, rocking, or toe-walking that goes beyond typical toddler exploration
• Intense distress with change — extreme reactions to changes in routine, environment, or expectations
• Unusual sensory responses — covers ears at everyday sounds, avoids certain textures, stares at lights or spinning objects

Signs in Preschoolers (2–4 Years)

By preschool age, the signs of autism often become clearer, especially in social situations where the differences between your child and their peers are more visible.

Social Signs

• Difficulty making friends — doesn’t know how to join play, prefers to be alone, or only interacts with adults
• Doesn’t understand emotions — has trouble recognizing facial expressions or understanding why someone is sad or happy
• Doesn’t engage in cooperative play — plays alongside but not with other children (parallel play persists beyond the typical age)
• Limited eye contact during conversation — looks away or past you during interactions

Communication Signs

• Echolalia — repeating words or phrases they’ve heard (from you, TV, books) instead of generating their own language
• Difficulty with back-and-forth conversation — talks at you rather than with you, doesn’t respond to questions, or gives unrelated answers
• Unusual speech patterns — monotone voice, unusual rhythm, speaking in a “scripted” way
• Difficulty understanding figurative language — takes things literally (“It’s raining cats and dogs” causes confusion)

Behavioral Signs

• Intense, focused interests — becomes deeply absorbed in a specific topic (trains, numbers, dinosaurs) to the exclusion of other activities
• Rigid routines — needs to follow the same path to school, eat the same food, use the same cup — deviations cause significant distress
• Sensory sensitivities — strong reactions to sounds, textures, tastes, smells, or visual input
• Difficulty with transitions — moving from one activity to another causes meltdowns or extreme resistance

Signs Across All Ages: Quick Reference

Age	Social Signs	Communication Signs	Behavioral Signs
6–12 months	Limited eye contact, doesn’t respond to name	Limited babbling, no gestures	Stiff or floppy body, limited facial expressions
12–18 months	Doesn’t point or show objects, limited imitation	No words, doesn’t follow directions	Repetitive movements, lines up objects
18–24 months	Doesn’t engage in pretend play, little peer interest	No two-word phrases, skill regression	Intense distress with change, unusual sensory responses
2–3 years	Difficulty with peers, parallel play persists	Echolalia, limited conversation	Intense interests, rigid routines
3–5 years	Difficulty making friends, misreads emotions	Scripted speech, literal interpretation	Sensory sensitivities, transition difficulties

Ready to explore evaluation options? Browse ABA clinics near you or take our screening quiz to understand your next steps.

What’s NOT Necessarily a Sign of Autism

It’s just as important to know what doesn’t automatically indicate autism:

• Being shy or introverted — some children are naturally quieter and take longer to warm up in social situations
• Late talking alone — speech delays have many causes (hearing issues, bilingual households, other developmental factors). Late talking without other signs isn’t enough for an autism diagnosis.
• Quirky interests — many children develop intense interests in specific topics. This is only concerning when it’s accompanied by other signs and significantly limits their engagement in other activities.
• Sensory preferences in isolation — not liking loud noises or preferring soft fabrics is common in many children
• Being active or energetic — high activity level alone is more associated with ADHD than autism. Learn about the differences between autism and ADHD.
• Tantrums — all toddlers have tantrums. It’s the intensity, frequency, triggers, and recovery time that distinguish typical tantrums from autism-related meltdowns.

The key is patterns. Autism is diagnosed based on a combination of signs across social communication and restricted/repetitive behavior — not any single behavior in isolation.

What to Do If You Notice Signs

If you’ve read through this list and several signs describe your child, here’s your action plan:

Step 1: Talk to Your Pediatrician

Share your specific observations. Be concrete: “My 18-month-old doesn’t point at things or respond to his name” is more actionable than “I think something might be wrong.” Bring notes or examples.

If your pediatrician suggests “wait and see,” you have every right to push for a referral or seek a second opinion. Research shows that parental concern is one of the strongest predictors of developmental differences — your instincts matter.

Step 2: Request M-CHAT Screening

The Modified Checklist for Autism in Toddlers (M-CHAT) is a validated screening tool for children 16–30 months. It takes about 5 minutes and can be done in your pediatrician’s office. The American Academy of Pediatrics recommends it at 18 and 24 months. If your child hasn’t been screened, ask for it.

Step 3: Get a Comprehensive Evaluation

A screening tool identifies risk — a comprehensive evaluation provides a diagnosis. Evaluations are conducted by developmental pediatricians, child psychologists, or multidisciplinary teams and typically include:

• Developmental history review
• Direct observation and interaction with your child
• Standardized assessment tools (like the ADOS-2)
• Cognitive and adaptive behavior testing
• Hearing test (to rule out hearing loss as a cause of language delays)

Evaluation waitlists can be long — 3 to 12 months in many areas. Get on the list now, even if you’re not 100% sure.

Step 4: Don’t Wait to Start Support

You do not need a diagnosis to begin intervention. While you wait for evaluation:

• Contact your state’s early intervention program (for children under 3) — these services are free and don’t require a diagnosis. Call your state’s Part C coordinator.
• Request school district evaluation (for children 3+) — public schools are required to evaluate children for developmental delays at no cost.
• Contact ABA providers — many offer initial consultations and can begin the assessment process. Browse providers near you.
• Start speech therapy — if language is a primary concern, a speech-language pathologist can begin therapy while you await a full evaluation.

Step 5: Breathe

This is a lot to process. It’s OK to feel scared, overwhelmed, or sad. It’s also OK to feel relieved — many parents feel validation when they realize their concerns are real and there’s a path forward.

Your child is the same child they were before you read this article. They haven’t changed. What’s changing is your understanding — and that understanding is the first step toward getting them the support they deserve.

If your child does receive a diagnosis, read our guide on what to do after an autism diagnosis for a step-by-step roadmap.

Early Intervention: Why Starting Now Matters

The research is clear: earlier intervention leads to better outcomes. Children who begin ABA therapy or other developmental supports before age 3 show:

• Greater improvements in language and communication
• Stronger social skills development
• More effective behavior management
• Higher rates of mainstream school placement
• Better long-term adaptive functioning

This doesn’t mean all hope is lost if your child is diagnosed later. ABA therapy and other interventions help at any age. But the brain’s plasticity during early childhood creates a unique window of opportunity that’s worth taking advantage of.

Learn more about why timing matters in our guide to early intervention with ABA therapy, or explore the research-backed benefits of ABA therapy.

Frequently Asked Questions

At what age can autism be detected?

Signs of autism can appear as early as 6 to 12 months, though they’re often subtle at this age. Most children show clearer signs by 18 to 24 months. Reliable screening is possible at 18 months using the M-CHAT, and a comprehensive diagnostic evaluation can be conducted as early as 18 to 24 months by experienced clinicians. The CDC reports that autism can be reliably diagnosed by age 2, though the average age of diagnosis remains around 4 years.

Can a child show signs of autism and not be autistic?

Yes. Many of the early signs of autism overlap with other conditions (speech delays, sensory processing differences, ADHD, anxiety) or may simply reflect normal developmental variation. That’s why a comprehensive evaluation by a qualified professional is so important — it considers the full picture, not just isolated behaviors. Even if your child doesn’t have autism, the evaluation may identify other areas where support would be beneficial.

What is the M-CHAT screening?

The Modified Checklist for Autism in Toddlers (M-CHAT) is a validated questionnaire for children 16 to 30 months old. It consists of 20 yes/no questions about your child’s behavior and development. A positive result doesn’t mean your child has autism — it means further evaluation is recommended. The M-CHAT is free, takes about 5 minutes, and is recommended by the American Academy of Pediatrics at 18 and 24 months. Ask your pediatrician about it.

Should I wait to see if my child “grows out of it”?

No. While some children with mild speech delays do catch up on their own, the research strongly supports early evaluation and intervention rather than a “wait and see” approach. If your child does have autism or another developmental difference, every month without support is a missed opportunity during the most critical period of brain development. If the evaluation shows no concerns, you’ve lost nothing except worry. If it identifies a need, you’ve gained precious time. Explore 10 signs your child could benefit from ABA therapy for more guidance.

Where do I go for an autism evaluation?

Options include: your pediatrician (for initial screening and referral), developmental pediatricians, child psychologists or neuropsychologists, autism-specific diagnostic centers, university-affiliated clinics, and your state’s early intervention program (for children under 3) or school district (for children 3+). Wait times vary — some private evaluators have shorter wait times than hospital-based programs. Ask your pediatrician for referrals, or browse our directory to find providers who offer assessments in your area.