Signs of Autism in Toddlers: What to Look For at 12, 18, 24, and 36 Months
The earliest signs of autism in toddlers are usually differences in social communication rather than anything dramatic: a child who doesn't turn when you say her name, doesn't point to show you things, doesn't look back at your face to share what he's excited about, or uses few gestures and little babble by the first birthday. Later signs include limited pretend play, repetitive movements, unusual sensory reactions, and intense distress at small changes. No single sign means autism, and no web page can diagnose your child. What this page can do is show you what clinicians look for, by area and by age, tell you what else these signs can mean, and give you the next steps, including the words to use with your pediatrician and the services you can start before any diagnosis. The frame for all of it comes from the first chapter of the book: you don't need a diagnosis to start helping your child.
Before the list: what this page can and can't tell you
Autism is diagnosed by a clinician who observes your child directly and takes a careful history. A checklist can tell you whether what you're seeing is worth a conversation; it can't tell you how that conversation ends. Many of the signs below also appear in children with hearing loss, isolated speech delay, global developmental delay, or a quiet temperament, which is why the section on what else it could be matters as much as the lists.
One thing to hold onto: Pierce and colleagues (2019, JAMA Pediatrics) found that in a large screening sample, autism diagnoses made as early as about 14 months were largely stable on follow-up. Careful evaluation in the second year of life is meaningful, and you don't have to wait until three for anyone to take you seriously. Nationally, the CDC's 2025 report puts the median age of diagnosis around 47 months, well after the age when signs typically appear; the gap between "a parent noticed" and "someone did something" is where this page is trying to help.
Signs by area
Several signs across more than one area are more concerning than one sign in one area.
Social communication
This is the core. Responding to their name typically emerges between 6 and 9 months; following your point and looking back and forth between a toy and your face, between 9 and 12 months; showing you things and pointing to ask for them, between 12 and 15 months; and pointing just to share something interesting, between 14 and 16 months. These behaviors are tied to joint attention, the ability to share focus on something with another person, which Mundy and Newell (2007) describe as one of the best-established early indicators of autism. If you point at a dog and say "Look!" most toddlers look at the dog and then back at you. Signs that often appear in toddlers later diagnosed with autism:
- Not responding consistently to their name by 12 months (Nadig and colleagues, 2007, found this one of the earliest reliable markers; see toddler not responding to name)
- Reduced or inconsistent eye contact, especially during interaction rather than when wanting something
- Not pointing to show you things by 18 months (pointing to request is a different skill from pointing to share)
- Not bringing you objects just to show them, and few gestures generally: little waving, reaching up, nodding, or head-shaking
- Delayed or reduced babbling, or babbling without the back-and-forth quality of a conversation
- Not imitating your sounds, facial expressions, or actions
- Flat or limited facial expression; not smiling back when smiled at
- Not following your point or your gaze
Jones and Klin (2013, Nature) found that attention to other people's eyes was present at two months in infants later diagnosed with autism and declined between two and six months. The differences start early and subtly, and nobody can see that without eye-tracking equipment.
Play
By 18 months most toddlers have started simple pretend play: feeding a doll, holding a block to their ear as a phone. The book flags pretend play as tightly linked to language and social development. Signs in play often include:
- No pretend play by 18 to 24 months
- Playing with parts of toys rather than the toy (spinning the car's wheels rather than driving it)
- Lining up, sorting, or stacking the same way repeatedly, with distress if the arrangement is disturbed
- Strong interest in household objects (remotes, light switches, fans) over toys
- Little interest in other children, or playing beside them without ever looking at them
Repetitive behaviors and sensory differences
Many autistic children show repetitive movements and intense sensory reactions, and sensory differences were added to the diagnostic criteria in the DSM-5 (2013). The book is careful to say these behaviors often help the child feel calm or in control.
- Hand-flapping, finger-flicking, rocking, or spinning, especially when excited or stressed
- Watching the same video segment or spinning object over and over
- Covering ears at everyday sounds, or extreme distress at haircuts, baths, or clothing textures
- Seeming not to notice loud sounds, cold, heat, or pain
- Intense fixation on routines, with meltdowns when the routine changes
Typically developing toddlers flap and spin sometimes too; what tends to differ in autism is the frequency, intensity, and how much the behavior serves a regulating purpose.
Motor
Some autistic children have delays in sitting, crawling, or walking; many hit those milestones on time. Motor signs are more often about how the body is used: walking on toes most of the time, unusual postures or hand movements, bumping into things, and difficulty imitating movements like clapping or the actions in songs.
Regulation
Toddlers on the spectrum often experience the world more intensely, so transitions and small changes can produce distress out of proportion to the event. One subtle sign the book highlights is reduced social referencing: when something startling happens, most toddlers glance at a parent's face to see how to react, and many autistic toddlers don't. At a loud birthday party, an autistic toddler may simply try to escape without ever checking your face.
Signs by age
These markers come from the book's milestone guide and from the CDC's 2022 "Learn the Signs. Act Early." checklists, which were revised so each milestone is one that most children (about 75 percent) have reached by that age. A child missing several, or losing ones they had, should be seen.
Signs of autism at 12 months
By 12 months most babies look when you call their name (the CDC places this at nine months), follow your point and look between a toy and your face, imitate simple sounds and gestures, wave, and babble with varied sounds; pointing itself usually arrives in the months just after the first birthday. Signs worth a conversation: not responding to name, no pointing or showing, little babbling, limited eye contact, not imitating, and not seeming to notice when you come and go.
Signs of autism at 18 months
By 18 months most toddlers use several words beyond mama and dada, bring you things to show you, point to show you something interesting, and have begun simple pretend play. The American Academy of Pediatrics (Hyman, Levy, and Myers, 2020) recommends autism-specific screening at this visit, so if your pediatrician doesn't offer it, ask. Signs at 18 months: no pointing to share, no or very few words, no pretend play, not responding to name, repetitive movements, and strong sensory reactions.
Signs of autism at 24 months (age 2)
By 24 months most toddlers combine two words ("more juice"), follow simple one-step directions, use gestures beyond pointing and waving, and have begun to play alongside other children. The AAP recommends a second autism-specific screen at this visit. Signs at age 2: no two-word phrases, speech that's mostly repeating what they've heard (echolalia) rather than their own combinations, no interest in other children, no pretend play, lining things up, and distress at small changes. If speech is the main concern, the speech delay vs autism page goes into that distinction in depth.
Signs of autism at 36 months (age 3)
By three, most children carry on a short back-and-forth conversation, ask questions, notice other children and join them, and play pretend with a storyline. Signs at age 3: language that's present but mostly scripted, not using language to share or ask about things, not seeking out other children, rigid play, rituals that can't be broken, and ongoing sensory sensitivities. At three, Early Intervention hands off to the school district's preschool special education program, which you can contact directly.
Regression: when skills disappear
Sometimes the first sign is a skill your child used to have and no longer does. The book calls developmental regression one of the most concerning red flags; it most commonly involves words a child used to say, gestures like waving and pointing, social engagement, and play, and the book places the typical window between 15 and 30 months.
A prospective study by Ozonoff and colleagues (2010) adds nuance: in infants later diagnosed with autism, declines in social engagement (looking at faces, smiling at people, responding to name) often began gradually in the second half of the first year, and many parents didn't recognize the loss as it was happening because it was so slow. If you're looking back and realizing your child used to do something she no longer does, you aren't imagining it, and you didn't miss anything a reasonable person would have caught.
Regression isn't caused by vaccines, parenting, or anything you did. Document what your child used to do and when it changed (video is ideal), tell your pediatrician specifically that you're seeing a loss of skills rather than a delay, and ask directly about autism screening and a specialist referral. Children who regress can and do make substantial progress, especially when support starts quickly.
Signs of autism in toddler girls
Girls are diagnosed less often and, on average, later than boys. The CDC's 2025 estimate is about 1 in 20 boys and 1 in 70 girls, and a meta-analysis by Loomes, Hull, and Mandy (2017, Journal of the American Academy of Child and Adolescent Psychiatry) put the true male-to-female ratio closer to 3:1 than the 4:1 long cited, which suggests a meaningful number of girls are being missed.
Why they're missed is still being worked out, and I'd rather be careful than confident here. Clinicians increasingly describe some autistic girls as presenting more subtly in toddlerhood: more eye contact than expected, repetitive interests that look conventional (dolls, animals, a favorite show), and distress that shows up as withdrawal rather than meltdowns. The core signs are the same (joint attention, response to name, interactive rather than scripted pretend play, flexibility), so for a girl the practical advice is to look at the quality of the social back-and-forth rather than the quantity, and to trust a persistent gut feeling even if the obvious markers aren't there.
What else could it be?
Hearing loss is the first thing to exclude whenever a child isn't responding to name or sounds, because it produces many of the same behaviors. Ask for a formal audiology evaluation rather than the office screening.
An isolated speech or language delay can look like autism at 18 to 24 months when the main thing you notice is the absence of words. The difference tends to be in everything around the words: a child with a speech delay alone usually points, shows, makes eye contact, imitates, pretends, and understands far more than they can say.
Global developmental delay and some genetic conditions can also produce overlapping signs. And some children are simply slow to warm or more interested in objects than people without being autistic. Temperament alone usually doesn't affect response to name, pointing to share, or pretend play, which is why those three carry so much weight.
What to do this week
If you've recognized your child in this page, here are the four steps I'd take in the next seven days.
1. Call your pediatrician and use these words. The book suggests asking directly: "Do you see signs that could suggest autism or a developmental delay?" Bring your top two or three concerns written down, specific examples of each, and short video clips if you have them. If the first answer is "let's wait and see," you're allowed to say you'd like a formal screening and a referral now.
2. Ask for the M-CHAT-R/F. The Modified Checklist for Autism in Toddlers, Revised with Follow-Up, is a 20-item parent questionnaire for children 16 to 30 months, validated by Robins and colleagues (2014, Pediatrics). It takes about five minutes, and a positive result after the follow-up questions means a formal evaluation is warranted; in the validation study, most children who screened positive had some developmental concern that needed attention, whether or not it turned out to be autism.
3. Refer your child to Early Intervention yourself. Every state has an Early Intervention program under Part C of IDEA for children from birth to age three. You don't need a diagnosis or a doctor's referral; parents are a primary referral source and can call directly, and federal rules require the evaluation and, if your child qualifies, the initial service plan within 45 days of referral. Search your state's name plus "early intervention" to find the number. If your child is three or older, contact your school district's special education office instead.
4. Start documenting. The book's "Tools for Tracking Concerns" section recommends short video clips of five things: response to name, eye contact and gestures, reactions to change, play with toys, and communication attempts. Keep a notes-app log of what you see and how often. This is what evaluators want, and it's far more useful than your memory under the stress of an appointment.
The checklist to bring to the pediatrician.
A one-page early signs checklist by age, the five video clips to take, and what to bring to the appointment, ready to print.
One email with the PDF, plus occasional early-intervention tips from Andrea. Unsubscribe anytime.
What to start at home today
None of the steps above require you to wait, and neither does this part. The book's position, which matches the research on parent-mediated intervention, is that the most impactful intervention your child can receive right now is you, in ordinary moments, using a few deliberate strategies. These help children who turn out to be autistic, children with isolated delays, and late bloomers alike, so there's no downside to starting before you have answers.
Build joint attention. Get on the floor, face to face. Bring toys up near your face, add a sound effect ("Whoa!"), pause, and wait for any glance toward you before you respond with delight. The book describes this as rebuilding the social loop one look at a time; the games are on the joint attention activities page.
Set up communication temptations. Put a favorite snack in a clear container your child can't open. Blow bubbles, close the lid, wait. Each setup creates a reason to look at you, reach, point, vocalize, or hand you something, and every one of those is communication to reward. The six home setups are on the communication temptations page.
Follow your child's lead. Join whatever your child is already doing, imitate it, and narrate it in short phrases. A child lining up cars has a parent beside her lining up cars and saying "red car, blue car." This is the foundation of the parent-mediated programs the book cites (JASPER, PACT), and it's where the first "she looked at me" moments tend to come from.
For the full plan, including how to sequence these over the first two weeks, see what to do while waiting for an autism evaluation.
Frequently asked questions
Can autism be diagnosed at 18 months?
Yes, by an experienced clinician. Pierce and colleagues (2019) found that diagnoses made from about 14 months in a large screening sample were largely stable at follow-up. Many evaluators prefer to see a child again around 24 to 30 months if the picture is unclear, but you don't need to wait until then to be screened, referred, or to start Early Intervention.
What is the M-CHAT, and can I take it myself?
The M-CHAT-R/F is a 20-question yes/no screener for children 16 to 30 months, validated by Robins and colleagues (2014). The questions are freely available, and you can complete the first stage yourself in about five minutes. The follow-up interview, which matters for accuracy, is meant to be done with a clinician, so bring your answers to your pediatrician rather than treating a home score as a result.
Is late talking a sign of autism?
It can be, and often it isn't. Many late talkers have isolated speech delays and catch up or do well with speech therapy. What distinguishes autism tends to be the surrounding skills: a late talker who points, shows, makes eye contact, imitates, and plays pretend is in a different situation from one who doesn't. Either way, a hearing test and a speech-language evaluation are the right first steps.
Do autistic toddlers smile and cuddle?
Many do. Some autistic toddlers are very affectionate, laugh easily, and seek hugs, especially deep-pressure ones. Evaluators look at joint attention, response to name, pointing to share, imitation, pretend play, and flexibility rather than at affection, and a child can be deeply cuddly and still show differences in all of those.
The checklist to bring to the pediatrician.
The early signs checklist by age, the five video clips to take, and the appointment prep list on one printable page.
One email with the PDF, plus occasional early-intervention tips from Andrea. Unsubscribe anytime.
If you're at the beginning of this, the start now guide lays out the first two weeks step by step, and the book and kit bundle has the full first chapter on early signs along with the printable tracking tools and the home strategies that follow.