About 1 in 31 children in the United States is now identified with autism spectrum disorder, so if you’re watching your child and wondering, you’re far from alone. Autism shows up differently in every child, but there are consistent patterns in how autistic children communicate, play, and respond to the world around them. Knowing what to look for can help you seek an evaluation early, when support makes the biggest difference.
Early Signs in Babies and Toddlers
The signs that tend to appear first are social ones. By around 12 months, most babies look up when you say their name, make eye contact during interactions, and follow your gaze when you point at something. A child on the autism spectrum may not do these things consistently, or may stop doing them after a period of typical development.
Between 12 and 24 months, watch for whether your child points at things to share interest (not just to ask for something), brings you objects to show you, or looks back and forth between you and a toy during play. These “joint attention” behaviors, where a child connects with another person over a shared experience, are among the earliest and most reliable indicators. A child who seems content to play alone and rarely checks in with you emotionally is worth paying closer attention to.
Other early signs include delayed or absent babbling by 12 months, no single words by 16 months, no two-word phrases by 24 months, and limited use of gestures like waving or nodding.
Repetitive Behaviors and Intense Interests
Autism involves more than social differences. To meet diagnostic criteria, a child also needs to show restricted or repetitive patterns of behavior. In young children, this can look like lining up toys in a specific order, spinning wheels on a car instead of driving it, flapping hands or rocking the body, or becoming very distressed by small changes in routine.
Some children develop an unusually intense focus on specific topics or objects. A toddler who is captivated by ceiling fans, light switches, or spinning objects for long stretches may be showing this pattern. Older children might memorize detailed facts about a narrow subject, like train schedules or dinosaur species, well beyond what’s typical for their age. These interests aren’t a problem on their own, but when they crowd out other types of play and learning, they become part of the broader picture.
Sensory Sensitivity
Many autistic children experience the sensory world differently. Some are hypersensitive: they cover their ears at sounds other children ignore, refuse certain food textures, become distressed by tags in clothing, or avoid being touched. Others are hyposensitive, meaning they seem to under-register sensory input. These children might not react to pain the way you’d expect, seek out intense pressure or movement, or stare closely at visual patterns and spinning objects.
A single child can be oversensitive in one area and undersensitive in another. Your child might gag at soft foods but crave deep-pressure hugs, or flinch at loud noises but seem unbothered by extreme cold. This uneven sensory profile is common in autism and can be one of the first things parents notice, sometimes before any social differences become obvious.
When Children Lose Skills They Already Had
Not every autistic child shows signs from birth. Some develop typically for a period and then lose skills they had already gained, a pattern called regression. The average age of onset is between 15 and 30 months. Language skills are the most commonly affected: a child who was using five or more meaningful words may stop talking, or a child who was using words to communicate may stop directing language at people altogether. About 74% of children who experience regression lose language-related skills specifically.
Regression can also affect social engagement, self-help skills like feeding or dressing, imaginative play, and purposeful hand movements. About 44% of children who regress lose skills outside of language. If your child was waving, pointing, or playing pretend and then stops, that’s worth discussing with your pediatrician promptly. Roughly 43% of children who experience regression do regain their lost skills, on average about 19 months later, especially with early support.
Why Girls Are Often Missed
Autism is identified more than three times as often in boys as in girls, but that gap likely reflects underdiagnosis rather than true prevalence. Girls with autism are more likely to camouflage their differences by copying the social behavior of peers, mimicking facial expressions, and rehearsing conversations. This masking can be effective enough to hide difficulties from teachers and even clinicians, delaying diagnosis by years.
Girls on the spectrum are also more likely to internalize their struggles. Instead of showing the disruptive or obviously repetitive behaviors that prompt referrals in boys, they may appear anxious, withdrawn, or simply “quiet.” Their restricted interests may look socially acceptable on the surface (an intense focus on animals, books, or a particular TV show) even when the depth and rigidity of the interest is unusual. Research shows that the effort of sustained masking comes at a cost: higher rates of psychological distress, exhaustion, and difficulty functioning over time. If your daughter seems to work unusually hard to fit in socially, or “falls apart” at home after holding it together at school, consider whether autism might be part of the picture.
How Screening and Diagnosis Work
Pediatricians in the U.S. typically screen all children for autism during routine well-child visits, often at 18 and 24 months. The most widely used screening tool is the Modified Checklist for Autism in Toddlers (M-CHAT), validated for children between 16 and 30 months. It’s a parent questionnaire, not a diagnosis. Children who score above the threshold are referred for a more thorough evaluation.
A full diagnostic evaluation is done by a specialist, such as a developmental pediatrician, child psychologist, or child neurologist. It typically involves structured observation of your child’s behavior, a detailed interview about their developmental history, and sometimes cognitive or language testing. Common assessment tools include the Autism Diagnostic Observation Schedule (ADOS-2), where a clinician interacts with your child through specific play-based activities, and the Autism Diagnostic Interview-Revised (ADI-R), a structured conversation with parents about the child’s behavior across development.
By age 2, a diagnosis made by an experienced professional is considered reliable. Many children aren’t diagnosed until later, particularly those with subtler presentations or stronger language skills, but the evaluation process is the same at any age.
What to Do if You See These Signs
You do not need a doctor’s referral or a formal diagnosis to access early support. If your child is under 3, you can call your state’s early intervention program directly and request a developmental evaluation. If your child is 3 or older, you can call any local public elementary school and request an evaluation for preschool special education services. Both options are federally funded and available at no cost to families.
If you’re unsure whether what you’re seeing is autism or just a different developmental pace, request the evaluation anyway. The process is designed to sort that out. Children who start receiving support before age 3 consistently show better outcomes in communication, social skills, and adaptive behavior than those who begin later. Waiting to see if a child “grows out of it” is the one approach that reliably doesn’t help.