Signs by age: what to pay attention to

Important right away. A single sign by itself is not a diagnosis. Doctors look at the pattern. When several things coincide, hold over time, or the child loses already acquired skills.

NICE advises not to look for "one typical sign." Instead, look at whether there is a combination of difficulties in social communication together with unusual behavior or sensory features.

Below is a guide by age. If something here describes your child, it is a reason to go through an assessment, but not a reason to panic.

0-12 months

• Responds little or unstably to their name.
• Rarely makes eye contact.
• Little social smile.
• Little babble or unusual babble.
• Weak response to the parents' voice.
• Few gestures.
• Does not reach for shared attention.

At this early age, suspicions are stated carefully. But if there are several signs at once, it is worth discussing with a pediatrician.

12-18 months

• Does not point with a finger to show something interesting.
• Does not bring objects to share.
• Does not imitate simple actions.
• Little or no words.
• Does not perform simple social games.
• Does not show objects to parents.
• Seems "not to hear" even though hearing is normal.

Here screening is already useful. AAP recommends developmental checks at 9 and 18 months, and a specific autism screening at 18 and 24 months.

18-24 months

• No two-word phrases.
• Loss of already acquired words or social skills.
• Limited interest in other children.
• Repetitive movements.
• Strong protest against changes.
• Unusual use of toys (lines them up instead of playing, looks at a car wheel for a long time).
• Sensory reactions. Covers ears, avoids touch, seeks strong sensations.

If there is a point about loss of skills, read the separate article "When to seek help urgently."

2-3 years

• Little role play (no "pretend" play).
• Difficulty in shared play with other children.
• Echolalia (repeats words, phrases, but without content).
• Limited interests.
• Rituals.
• Difficulty with transitions between activities.
• Difficulty with requests, communication, understanding spoken language.

3 years and older

• Difficulty with friends.
• Literal understanding of language (does not get jokes, metaphors).
• Difficulty with others' emotions.
• Unusual or very intense interests.
• Social anxiety or isolation.
• Masking of symptoms, especially in girls.

A note about girls

A 2025 systematic review showed that girls more often mask difficulties. They adjust, copy, hide. Because of this, they are often diagnosed later.

If a girl imitates well, has "acceptable" but very intense interests, gets exhausted after socializing, understands language literally, does not catch social nuances, or "falls apart" at home after kindergarten, it is worth going through a full assessment.

The phrase "she is contactful, so it is not autism" is not a reliable argument. The same as with boys.

What is NOT a sign of autism

Some things scare parents, although by themselves they are not signs of autism.

• The child at 1.5 years is not speaking yet but shows with gestures, responds to their name, makes eye contact. This may simply be a slower pace of speech.
• The toddler is strongly attached to one toy. Normal age norm.
• The child is shy around new people. This also happens.
• The toddler sometimes twirls their hands when happy. Repetitive movements in ASD are persistent and arise in many situations, while a simple joyful reaction is not.

One sign is not a diagnosis. A persistent pattern from several areas is a reason for assessment.

How to observe so that it is useful

Do not record "something is wrong" abstractly. Record concretely.

What is useful to write down now.

• Response to name. Whether they respond, how many times you need to call, in which situations not.
• Eye contact in natural situations.
• Gestures, especially pointing.
• Shared attention. Whether they show you something interesting, whether they look where you point.
• Imitation. Claps, waves "bye."
• Play. How they play, whether there is "pretend."
• Words and phrases, echolalia.
• Reaction to routine changes.
• Sensory reactions.
• Contacts with other children.
• Loss of skills, if any.

Short videos from everyday situations help a lot. Name, request, shared play, transition between activities. This is not proof, but it is a guide for the doctor.

What is next

If something in this description sounds familiar, the next step is not self-diagnosis. Read "When to seek help urgently" and "Who to see and in what order."