Early signs of autism in toddlers: what to notice at 12, 18, and 24 months

Children develop on their own timelines, and a wide range is normal. At the same time, a few early patterns are consistently associated with autism, and noticing them early gives a family more options. Below is what clinicians look for at three common checkpoints, drawn from the developmental research used in standard screening tools such as the M-CHAT-R and from the CDC’s developmental milestones.

Around 12 months

By the first birthday, most babies are intensely social. They look where you point, point themselves to show you things, wave, and respond when you say their name. They babble back and forth and watch your face closely.

Differences worth noting at this age include:

• Rarely responding to their name, even though hearing seems fine
• Little or no pointing, waving, or reaching up to be picked up
• Not following your point or gaze to look at something together
• Limited babbling, or babbling that is not directed at anyone
• Less eye contact and fewer shared smiles than you would expect

Hearing should be checked whenever a child is not responding to sound. A hearing difference can look very similar to some of these signs, and it is easy to rule in or out.

Around 18 months

Eighteen months is when pediatricians first screen for autism, because the signs become clearer. Most toddlers now use a handful of words, point to things they want and things they find interesting, imitate what adults do, and play simple pretend games such as feeding a doll or talking on a toy phone.

At this age, clinicians pay attention to:

• Pointing to request things but rarely pointing just to share interest
• Few or no words, or words that appeared and then faded
• Little imitation and little pretend play
• Strong interest in parts of objects, such as spinning wheels, over the whole toy
• Repetitive movements such as hand flapping or rocking, especially when excited or upset
• Unusual reactions to sounds, textures, or lights

Around 24 months

By two, most children combine two words, follow simple directions, bring things to show you, and are very interested in other children even if they do not yet play together. They use their whole face and body to communicate.

Signs that may prompt an evaluation at this age include:

• Not yet combining words, or using language mostly to repeat what others say
• Difficulty with back-and-forth interaction: games, conversation, shared play
• Limited interest in other children
• Intense, narrow interests or strong need for routines, with distress when they change
• Any loss of words or social skills the child previously had

What these signs do not mean

Many autistic toddlers make eye contact, are affectionate, and reach language milestones on time. Many children with one or two of the differences above are not autistic. The signs are starting points for a conversation, not a diagnosis. A thorough evaluation looks at the whole picture across settings, and considers other explanations such as hearing differences, language disorders, or global developmental delay.

Why early identification matters

Autism can be diagnosed reliably by age two by an experienced clinician, and the diagnosis is stable over time. The reason to act early is practical. Missouri’s early intervention program, First Steps, serves children under three. Insurance authorization for therapy typically requires a diagnostic report. Preschool and school supports depend on documentation. Every one of those doors opens sooner with an evaluation in hand.

Early identification is also not about changing who a child is. It is about understanding how they learn and communicate, so the adults around them can meet them there.

What to do next

1. Write down what you notice, with rough ages. Specific examples are more useful to a clinician than general worry.
2. Ask your pediatrician for autism screening if it has not been done, and request a referral for a diagnostic evaluation if the screen is positive or your concern persists.
3. Contact an evaluation practice directly. In Missouri you do not need a referral to be evaluated. Some insurance plans require one for payment, which the practice can check for you.
4. Request a First Steps evaluation if your child is under three. It is free, does not require a diagnosis, and can run alongside a diagnostic evaluation.

This article is general information, not medical advice, and does not replace an evaluation by a qualified clinician. If you have concerns about your child’s development, talk with your pediatrician or a developmental specialist.