Early Signs of Autism by Age: What to Look For

Few questions sit more heavily with a parent than whether their child might be autistic. The signs of autism can appear early, but they're often subtle, easily mistaken for personality or “just a phase,” and they vary enormously from child to child. This post offers a calm, age-by-age guide to what to look for — written not to alarm you, but to help you observe clearly. For the subtler indicators that are most often overlooked, pair this with our post on early autism signs parents often miss.

A Note Before We Begin

Autism is a spectrum, which means it shows up differently in every child. No single sign confirms or rules it out, and many autistic traits appear, to a lesser degree, in children who are not autistic. What matters is the overall pattern, observed consistently over time. Reading this list should make you a better observer, not a self-appointed diagnostician — only a qualified professional can assess for autism.

Signs That May Appear by 12 Months

In the first year, possible early signs include limited eye contact, not responding to their name by around 9–12 months, few or no gestures such as pointing or waving, and limited back-and-forth sharing of smiles and expressions. Babbling may be reduced. Because so much first-year development is about connection and communication before words, differences here often show up in how a baby relates rather than in any single skill. Our post on communication is more than speech explains why these pre-verbal signals matter so much.

Signs That May Appear by 18 Months

By around a year and a half, signs can include not pointing to show you interesting things (sharing, rather than just requesting), limited pretend play, little interest in other children, not following simple gestures like a point, and reduced response to their name. A particularly important sign at any age is loss of skills — a child who had words or social warmth and then seems to lose them. This always warrants a prompt professional conversation.

Signs That May Appear by 2 to 3 Years

As language and play would normally be blossoming, possible signs include delayed or unusual speech, repeating words or phrases out of context (echolalia), strong preferences for routine and distress at change, intense focus on particular objects or topics, repetitive movements such as hand-flapping or lining up toys, and difficulty playing or engaging with peers. Sensory differences — being unusually sensitive to sounds, textures or lights, or seeking out certain sensations — often become more noticeable in this window too. Many of these overlap with everyday toddler behaviour, which is exactly why the pattern over time matters more than any single moment. Difficulty with change, for instance, is common in many children, as we discuss in understanding transitions.

Signs in the Preschool Years

In older preschoolers, signs may include difficulty with the give-and-take of conversation, trouble reading others' feelings or social cues, a preference for playing alone, very literal understanding of language, and continued reliance on routine and sameness. Some children mask or compensate, which can make signs harder to spot — especially in children who are verbal and academically able.

What to Do If You Recognise These Signs

If several of these signs resonate, the most useful next step is observation followed by a professional conversation — not alarm. Note what you see, across different days and settings, and raise it with a paediatrician. Our post on what to do when you suspect your child has autism walks through this calmly, and the signs your child may benefit from early intervention can help you decide whether to seek support now.

Crucially, you don't have to wait for a diagnosis to begin helping your child. The skills that early support builds — communication, play, regulation, social connection — benefit any child who finds them difficult, label or no label.

At ABA Labs, we provide developmental assessments, early intervention and behaviour support tailored to each child. If something here resonates and you'd like to talk it through, book a consultation — there's no pressure, just guidance.

Autism can only be diagnosed by qualified professionals. This guide is for awareness and is not a diagnostic tool. If you're feeling worried about your child, speaking with a paediatrician is always a sound next step.