Signs of Autism in Toddlers: Early Symptoms by Age
What to look for at 12, 18, 24 and 36 months, which red flags matter most, and when to ask your pediatrician for an evaluation.
Early signs of autism, age by age
Recognising autism early opens the door to support that clearly improves outcomes. Signs cluster in three areas: social communication, restricted or repetitive behaviour and sensory responses. This guide summarises the red flags at 12, 18, 24 and 36 months in plain language — without alarmism — and gives you structured observation forms so your notes reach the pediatrician as evidence, not as a vague worry.
Key benefits
Age by age
Specific signs at 12, 18, 24 and 36 months.
Structured observation
Forms to log what you actually see at home.
Share with your doctor
Export your observations as a PDF.
No alarmism
Clear, evidence-informed information.
What's included
- Red-flag checklist for each age band.
- Structured observation and milestone diary.
- PDF export for pediatrician appointments.
- Guidance on what happens after a referral.
- Family-friendly learning resources.
- Docky AI assistant for your questions.
- Private community of parents.
- Multilingual and privacy-first.
Start logging your observations today
One structured record is worth more than dozens of late-night searches.
Try free for 7 daysFrequently asked questions
What are the earliest signs of autism in toddlers?+
Limited response to their name, little eye contact, few social smiles, not pointing or waving, delayed babbling or speech, and repetitive play with objects such as lining up or spinning toys.
At what age can autism be detected?+
Signs often appear between 12 and 24 months. A reliable diagnosis can be made from around 18-24 months by a specialist team, and screening is recommended at 18 and 24 months.
My toddler is not talking — is that autism?+
Speech delay alone is not autism. Clinicians look at the whole picture: social communication, gestures, shared attention, play and repetitive behaviours. Speech delay is still a reason to seek an evaluation.
What should I do if I suspect autism?+
Talk to your pediatrician and ask for a developmental evaluation or early intervention referral. You do not need a diagnosis to start early support, and earlier support means better outcomes.
Does AutismDock diagnose autism?+
No. AutismDock does not replace a clinical diagnosis. It gives you structured observation forms and a milestone diary you can export as a PDF to share with your pediatrician or specialist.
Can autism signs look different in girls?+
Yes. Autistic girls more often mask difficulties, imitate peers and show subtler social differences, which is one reason they are diagnosed later on average.