CDC's page describing common signs of autism by age — social, communication, and behavioural — written for parents trying to make sense of what they are noticing before talking with a doctor.
Many families come to autism the same way: not with a single dramatic moment, but with a slow accumulation of small differences. A child who does not turn when called. A toddler who lines things up with unusual focus. A two-year-old with few words but a deep, quiet world. The US Centers for Disease Control and Prevention keeps a clear list of early signs, grouped so parents can make sense of what they are noticing before a doctor's visit.
Signs in how a child connects
The signs that most often bring families to an assessment involve social communication. A young autistic child might avoid or rarely use eye contact, not respond to their name by their first birthday, show few facial expressions aimed at others, or not point to share something interesting. They may not play "pretend" games in the way peers do, or may seem happiest in their own company. None of these is a fault — they are differences in how a child is oriented to other people.
Signs in language
Language differences are common and varied. Some autistic children are late to talk; some talk early and precisely but find back-and-forth conversation hard. You might notice repeated words or phrases (echolalia), talking mostly about a favourite topic, or taking language very literally. A child who used words and then seemed to lose them is a specific pattern worth raising with a doctor promptly.
Signs in behaviour and the senses
The second cluster is restricted and repetitive patterns: lining up toys, repeating movements such as rocking or hand-flapping, intense and narrow interests, and a strong need for routine — with real distress when it changes. Sensory differences sit here too: covering ears at ordinary sounds, discomfort with certain textures or clothing labels, seeking out spinning or deep pressure, or eating a very narrow range of foods. These behaviours often serve a purpose for the child, usually regulation.
Signs are a starting point, not a verdict
A single sign means little; every child does some of these sometimes. What matters is a consistent pattern across the social and behavioural clusters, and whether it is affecting daily life. The CDC organises its milestone checklists by age, from two months to five years, precisely so parents can track patterns over time rather than react to one moment.
What to do next
If several of these ring true, write down what you see — with rough dates and examples — and take it to your child's doctor or a health visitor. Ask specifically about developmental screening, and do not be put off by "let's wait and see" if your instinct says otherwise; you can always ask for a referral. Trust your observations: parents notice real differences long before formal testing catches up, and acting on a concern early opens the door to support sooner. Raising a question is not labelling your child; it is giving them the best chance of being understood.