Early Signs of Autism: A Parent’s Guide by Age

Parents know their children closely. Sometimes a concern begins with something small: your baby does not seem to respond to their name very often, your toddler uses fewer gestures than expected, speech is developing differently, or certain sounds and changes in routine seem unusually difficult. 

If you are searching for the early signs of autism, it is important to start with one reassuring fact: no single behaviour can tell you whether a child is autistic. 

Children develop at different rates, and many behaviours associated with autism can also occur for other reasons. Autism can also look very different from one child to another. Some children show noticeable developmental differences during infancy or toddlerhood, while for others the pattern becomes clearer later, particularly as communication and social expectations increase. 

The NHS notes that signs of autism may be noticed at a very young age or may not become apparent until later, and that autistic children will not necessarily show every commonly described characteristic. NICE similarly advises professionals to consider a child’s overall development rather than interpreting individual behaviours in isolation. 

This guide explains autism signs by age, including signs of autism in babies, signs of autism in toddlers and developmental differences that may become more noticeable around ages 2 and 3. It is intended to help parents know what to observe and when a conversation with a qualified professional may be helpful — not to diagnose a child. 

Important: Developmental screening, milestone monitoring and online checklists cannot diagnose autism. If you have concerns about your child’s development, speak with an appropriately qualified healthcare or developmental professional. 

Early Signs of Autism: What Parents May Notice 

Early developmental signs of autism usually involve patterns across more than one area, rather than one isolated behaviour. 

Parents may notice differences in: 

• social interaction and shared attention 
• eye contact or use of facial expressions 
• response to their name or another person’s voice 
• gestures such as pointing, showing or waving 
• speech and other forms of communication 
• imitation and social play
• repetitive movements or repetitive ways of playing 
• responses to sounds, textures, lights, movement or other sensory experiences ● flexibility around routines and transitions 
• particularly strong or focused interests 

Some parents search for these characteristics as “early autism symptoms” or “autism red flags”. However, they are better understood as developmental patterns that may be worth discussing with a healthcare professional, especially when several occur together, persist over time or are accompanied by a loss of previously acquired skills. 

Developmental milestone information can provide useful context, but milestone checklists are not diagnostic tools. The CDC specifically distinguishes milestone monitoring from validated developmental screening. 

Autism Signs by Age: A Quick Overview 

Age Areas parents may notice 

0–12 months 

Pointing and showing, gestures, imitation, responding to name, babbling or emerging words, shared attention and repetitive play or movement 

12–18 months 

Language development, social communication, pretend play, repetitive behaviours, sensory differences and responses to changes 

18–24 months 

Social engagement, eye contact, response to voices or name, facial expressions, early gestures, shared enjoyment and unusual sensory responses 

Age 2 Communication differences, limited back-and-forth interaction, repetitive play, sensory sensitivities, strong routines or focused interests 

Age 3 Conversation, peer interaction, imaginative play, social reciprocity, repetitive behaviour, sensory differences and increasing difficulty with unexpected change 

These are areas for observation, not diagnostic criteria for parents to apply at home. A child’s developmental history, behaviour across different situations and individual strengths and needs all matter. 

Signs of Autism in Babies: 0–12 Months 

Some parents wonder whether signs of autism in babies can be noticed during the first year. 

They sometimes can, particularly towards the latter part of the first year, but differences during infancy can be subtle and non-specific. Many babies who are later diagnosed with autism may not have obvious signs during their earliest months.

Rather than looking for one specific behaviour, it can be more useful to observe how your baby communicates and engages with people over time. 

Social engagement 

Babies gradually become increasingly interested in social interaction. A parent might want to discuss development with a professional if, over time, they notice their baby seems to engage with people less often than expected for their developmental stage. 

For example, the baby may appear less interested in interactive games, faces or sharing enjoyment. 

That does not mean that a quiet, independent or less socially responsive baby is autistic. Temperament, hearing, developmental stage and many other factors can influence social behaviour. 

Eye contact 

Some autistic children use eye contact differently or less frequently. 

However, limited eye contact by itself does not mean autism, and good eye contact does not rule autism out. NICE specifically advises professionals not to exclude autism simply because a child makes good eye contact, smiles or shows affection. 

What may be more informative is the broader pattern of how a baby combines looking, facial expression, sounds and gestures to communicate with another person. 

Response to voices and name 

During the later part of the first year, parents may begin noticing how consistently a baby responds to familiar voices or their name. 

An inconsistent response can have many explanations, including attention, temperament or hearing differences. If a baby regularly seems not to hear voices or sounds, discussing hearing as well as development with a professional can be useful. 

Facial expressions and shared enjoyment 

Parents may notice differences in how frequently their baby exchanges smiles, facial expressions or excitement with them. 

Again, variation is considerable. What matters more than one missed response is a persistent pattern across interactions. 

Early gestures 

By around the end of the first year, many babies begin using gestures such as waving and increasingly communicate through movements, sounds and expressions. CDC

developmental guidance includes waving “bye-bye” among milestones commonly seen by 12 months. 

Using very few gestures may be worth mentioning during a developmental discussion, particularly alongside other communication differences. 

Shared attention 

Shared attention means two people focusing on the same thing together — for example, a baby looking towards something interesting and then back towards their parent. 

This social-communication skill develops gradually. Differences in shared attention can be associated with autism, but they must be interpreted in the context of the child’s broader development. 

Sensory responses 

Some babies may react strongly to particular sounds, lights, textures, movement or touch, while others may appear unusually unresponsive to certain sensations. 

Sensory differences occur in autistic people, but they also occur in children who are not autistic. The NHS describes both unusually strong and unusually limited responses to sensory input among characteristics that can occur in autistic children. 

Early Signs of Autism at 12–18 Months 

Between the first and second birthdays, social communication develops quickly. This is also a period when some early signs of autism in toddlers may become easier to notice. 

A parent may begin to notice differences involving several of the following areas.

Pointing and showing 

Young toddlers increasingly use gestures to communicate. 

They may point because they want something, but they may also point simply to show another person something interesting. 

At 15 months, CDC developmental guidance includes showing a parent an object they like and pointing to ask for something or get help. By 18 months, pointing to show something interesting is included among common developmental milestones. 

A child who rarely points, shows objects or tries to direct another person’s attention may be worth discussing with a professional, particularly if there are other communication differences. 

Gestures

Gestures can include: 

• waving 
• reaching 
• nodding 
• pointing 
• holding something up to show another person 
• using facial expressions alongside sounds or words 

Some autistic toddlers use fewer gestures, use them differently or develop them later.

Responding to name 

Repeatedly not responding to their name can be one of the developmental differences associated with autism. 

But there are other possible explanations, including hearing difficulties or a child being very absorbed in an activity. It should never be interpreted as a diagnosis on its own. 

Imitation 

Toddlers often begin copying actions they see other people perform. 

A child who rarely imitates gestures, sounds, facial expressions or simple actions may show a social-learning difference worth exploring, particularly alongside other developmental concerns. 

Babbling, words and communication 

Some autistic children develop spoken language later than expected, while others begin speaking within the expected developmental range. 

It can therefore be more useful to look at how a child communicates, not simply how many words they use. 

For example: 

• Do they use sounds, gestures or words to get another person’s attention?
• Do they communicate mainly to request things, or also to share interest?
• Do they combine looking, gestures and sounds? 
• Do they seem interested in communication with other people? 

Speech delay alone is not enough to indicate autism. 

Shared attention 

A toddler might see an aeroplane, look towards it and then look towards their parent as if to say, “Did you see that too?”

This type of shared attention is an important social-communication skill. 

If a toddler rarely tries to share experiences, objects or interests with another person, it may be worth discussing alongside their other developmental characteristics. 

Play and repetitive behaviours 

Some toddlers may repeatedly spin wheels, arrange objects in particular ways, open and close doors, repeat the same action or become very interested in specific aspects of a toy. 

Repetitive behaviours can be associated with autism, but repetition is also a normal part of toddler learning. The important questions are how frequent or intense the behaviour is, whether it appears alongside other developmental differences and whether it affects everyday activities. 

Signs of Autism at 18–24 Months 

Between 18 and 24 months, differences in social communication, language and play may become more noticeable. 

Autism can sometimes be identified during this period, although diagnostic certainty varies between children. NICE notes that diagnostic uncertainty can be greater in children under 24 months, while CDC guidance states that autism can sometimes be detected by around 18 months. 

Language development 

Possible differences may include: 

• using few spoken words 
• developing words more slowly 
• repeating particular sounds, words or phrases 
• using words mainly to request rather than to share socially 
• using language in an unusual or highly repetitive way 
• having difficulty understanding spoken language 

However, some autistic toddlers have age-appropriate or advanced spoken language. Speech level alone cannot determine whether a child is autistic. 

By 18 months, developmental guidance includes attempting several words in addition to names such as “mama” or “dada”. By age 2, combining at least two words is among CDC’s general communication milestones. These milestones provide developmental context rather than diagnostic thresholds. 

Social communication 

Parents may notice that their toddler:

• uses fewer gestures to communicate 
• rarely shows objects simply to share interest 
• seems less interested in back-and-forth interaction 
• does not consistently look between an object and another person 
• appears to communicate mainly when they need help or want something Again, the pattern matters more than any one example. 

Pretend play 

Pretend play develops gradually during the toddler and preschool years. 

Some autistic children use toys repetitively rather than symbolically or show less spontaneous pretend play. Others do engage in imaginative play. 

The presence of pretend play therefore does not rule autism out, something NICE specifically highlights. 

Repetitive movements 

A toddler may repeatedly: 

• flap their hands 
• rock 
• spin 
• pace 
• flick their fingers 
• repeat a particular movement 

Repetitive movement, sometimes called stimming, can serve many purposes, including enjoyment or self-regulation. It should not automatically be treated as a behaviour that needs to be stopped. 

The NHS includes repetitive movements among behaviours that can occur in autistic children. 

Sensory differences 

A toddler may be particularly sensitive to: 

• vacuum cleaners or other loud sounds 
• certain clothing or food textures 
• bright lights 
• hair brushing or washing 
• touch 
• crowded or noisy environments 

Other children may actively seek particular sensations such as spinning, jumping, pressure, movement or specific textures.

Responses to changes 

A young child may become distressed when: 

• a familiar route changes 
• an activity ends unexpectedly 
• food is presented differently 
• a familiar routine changes 
• an expected object is unavailable 

All toddlers can struggle with transitions. What may be worth exploring is an unusually strong, persistent pattern that significantly affects everyday life, particularly when other developmental differences are present. 

Loss of previously acquired skills 

If a child loses language, social or other developmental skills that they previously used, discuss this promptly with a healthcare professional. 

NICE specifically recommends autism-team referral for children under 3 who experience regression in language or social skills and recommends medical assessment for motor regression. 

Regression does not automatically mean autism, which is one reason professional assessment is important. 

Signs of Autism at Age 2 

For many families, signs of autism at 2 years become easier to recognise because children are increasingly communicating, exploring, imitating adults and engaging socially. 

If you are searching for signs my child may have autism, try to consider patterns across several areas rather than comparing one skill with another child of the same age. 

Communication differences 

A 2-year-old may: 

• use less spoken language than expected 
• use words but have difficulty using them socially 
• repeat words or phrases 
• communicate largely by pulling an adult towards something they want
• use fewer gestures 
• have difficulty following or understanding everyday language 

Some autistic 2-year-olds communicate effectively without spoken language, while others speak in phrases or sentences.

Social interaction 

Parents may notice: 

• limited back-and-forth social interaction 
• less frequent sharing of interests 
• fewer attempts to involve another person in play 
• less interest in other children’s activities 
• unusual responses to another person’s expressions or emotions 

None of these behaviours is diagnostic by itself. 

Repetitive movements 

Hand flapping, rocking, spinning or other repeated movements may become more obvious. 

These movements can be regulating, enjoyable or expressive for a child. Their presence should be considered alongside the child’s overall pattern rather than treated as an isolated warning sign. 

Repetitive play 

A child might: 

• repeatedly line up objects 
• focus on spinning parts of a toy 
• repeatedly open and close something 
• play with objects in the same sequence 
• become distressed if their arrangement is changed 

Repetitive play is not unique to autism. Many young children enjoy repetition because it helps them learn and predict what happens next. 

Sensory sensitivities 

The child may strongly avoid or seek certain sounds, tastes, smells, textures, movements or visual experiences. 

Food selectivity can sometimes be connected to sensory differences, although feeding difficulties have many potential causes. 

Difficulty with transitions 

Moving from one activity to another may be particularly difficult, even when the change seems small to adults. 

Visual predictability, preparation and consistent routines may help some children regardless of whether they have an autism diagnosis.

Strong or unusual interests 

Some toddlers develop unusually intense interest in a particular object, topic, movement, symbol or activity. 

Strong interests can also be enjoyable strengths. The clinical relevance depends on the wider developmental picture and how the interest affects everyday functioning. 

Signs of Autism at Age 3 

Signs of autism at 3 years may become more noticeable as expectations around conversation, peer play, flexibility and imaginative play increase. 

A child who coped comfortably in a familiar home environment may show more visible differences when they begin nursery or spend more time with other children. 

Conversational communication 

By around age 3, many children are increasingly participating in back-and-forth conversations. CDC developmental guidance includes two or more conversational exchanges among milestones commonly observed by this age. 

An autistic child might: 

• find conversational turn-taking difficult 
• speak mainly about preferred interests 
• repeat phrases they have heard 
• use language in an unusually formal or repetitive way 
• have difficulty answering open questions 
• use little spoken language 

A child’s communication strengths may look very different depending on the individual.

Peer interaction 

Some children may: 

• prefer playing alone 
• watch other children without joining them 
• want to interact but be unsure how 
• approach peers in ways that seem different 
• find group play overwhelming 
• prefer predictable interactions with familiar adults 

Social differences should not automatically be interpreted as a lack of interest in other people. 

Imaginative play

Some autistic children have less spontaneous pretend play or use toys differently from peers. 

Others have rich imaginative worlds and extensive pretend play. 

Again, autism cannot be ruled in or out based on one type of play. 

Social reciprocity 

Social reciprocity describes the natural back-and-forth of interaction. Parents might notice differences in: 

• taking turns during interaction 
• sharing excitement 
• responding to another person’s attempts to engage 
• adapting communication to the other person 

These differences can be subtle, particularly in verbally able children.

Repetitive behaviour 

Repeated movement, phrases, routines or play patterns may continue or become more noticeable at this age. 

Sensory differences 

A 3-year-old may be able to communicate more clearly that certain environments, clothing, foods, noises or sensations are uncomfortable. 

This can help parents recognise that behaviour previously interpreted as a “tantrum” may sometimes reflect sensory overload, difficulty communicating or distress around unpredictability. 

Routines and predictability 

Some children may strongly prefer familiar: 

• meals 
• routes 
• activities 
• sequences 
• clothing 
• bedtime routines 
• ways of arranging objects 

Unexpected change can feel genuinely difficult rather than simply undesirable.

What Are the Main Signs of Autism? 

Autism is diagnosed based on a broader developmental pattern rather than any one characteristic. 

For parents trying to understand the developmental signs of autism, it may help to group observations into several broad areas. 

Social communication 

Possible differences include: 

• less frequent use of eye contact 
• fewer gestures 
• inconsistent response to name 
• differences in sharing attention or enjoyment 
• difficulty with conversational back-and-forth 
• differences in understanding or using non-verbal communication 
• less interest in, or different approaches to, peer interaction 

Remember that autistic children can make eye contact, show affection, laugh, form close relationships and enjoy social interaction. NICE specifically warns against ruling autism out because these behaviours are present. 

Repetitive behaviours 

These can include: 

• rocking 
• hand flapping 
• spinning 
• repeated movements 
• repeating words or phrases 
• arranging objects 
• playing in repeated patterns 
• repeatedly focusing on certain parts of objects 

The NHS recognises repetitive actions and movements as characteristics that can occur in autistic children. 

Sensory differences 

A child may be unusually sensitive or less responsive to: 

• sound 
• light 
• touch 
• smell
• taste 
• temperature 
• pain 
• movement 
• textures 

They may also actively seek particular sensory experiences. 

Restricted or intense interests 

Some autistic children become deeply interested in particular subjects, objects or activities. 

The subject itself does not necessarily appear unusual. It may be the intensity, focus or importance of the interest that stands out. 

Developmental differences 

Parents may notice differences involving: 

• language 
• gestures 
• play 
• social attention 
• imitation 
• emotional regulation 
• flexibility 
• learning patterns 
• motor or self-care development 

A child may be ahead in one developmental area and need more support in another. 

That uneven profile is one reason looking at the whole child is more useful than checking individual behaviours against a list. 

Does Every Autistic Child Show the Same Signs?

No. 

Autism is a spectrum, and autistic children are highly diverse. 

Two autistic children of the same age may have very different: 

• communication styles 
• sensory profiles 
• strengths 
• interests 
• learning styles 
• support needs
• ways of interacting socially 
• developmental trajectories 

One child may communicate mainly without speech, while another may have extensive vocabulary but find reciprocal conversation difficult. 

One may actively seek social interaction but find social cues confusing. Another may prefer less interaction or need more time to feel comfortable. 

One may find sound overwhelming, while another actively seeks loud or repetitive sounds. Some children display obvious repetitive behaviours; in others they may be subtle. 

Autism can also be less readily recognised in some children. NICE highlights that autism may be under-recognised in girls and can be missed in verbally able children. The NHS also notes that some autistic children may mask or adapt their behaviour in ways that make characteristics less obvious. 

This is why autism should not be treated as a checklist where a child must display every commonly described characteristic. 

When Should Parents Seek Professional Advice? 

You do not need to wait until a particular birthday if you are genuinely concerned about your child’s development. 

Consider speaking with a professional if: 

• you consistently notice differences in communication, play or social interaction
• your child is not developing skills you expected and you are concerned
• several developmental differences occur together 
• sensory difficulties significantly affect everyday life 
• your child has substantial difficulty communicating their needs 
• nursery or other caregivers have also raised developmental concerns
• your child has lost skills they previously used 
• you are simply worried and would like professional developmental guidance 

NICE specifically states that parents’ concerns about development or behaviour should be taken seriously, even when other people have not noticed the same thing. 

Depending on where you live and your child’s needs, you might speak with a: 

• GP 
• health visitor 
• paediatrician 
• developmental specialist 
• speech and language therapist 
• other appropriately qualified child-development professional

A speech and language therapist can assess and support communication needs, but an autism diagnosis generally involves a broader specialist assessment rather than one professional judging one area of development. 

If your child has lost previously acquired skills, particularly language, social or motor skills, raise this promptly with a healthcare professional. 

What Happens After You Raise a Concern? 

The exact pathway varies between healthcare systems and local services, but the process may involve several stages. 

1. Developmental discussion 

A professional will usually ask about your child’s development, communication, play, behaviour, medical history and the specific differences you have observed. 

Examples from everyday life can be helpful. 

Instead of saying only, “He doesn’t communicate,” you might explain: 

“My son usually takes my hand to the cupboard when he wants food but rarely points to show me things.” 

Specific observations give professionals more useful information. 

2. Developmental or autism screening where appropriate

You may be asked to complete a structured questionnaire or screening tool. Autism screening is not diagnosis. 

Screening tools are intended to identify children who may benefit from further evaluation. CDC guidance states clearly that screening does not provide conclusive evidence or produce a diagnosis, and NICE advises that identification tools should not be used by themselves either to make or rule out an autism diagnosis. 

A positive screen therefore does not mean that a child is definitely autistic. 

Likewise, a negative screen cannot always rule autism out if meaningful developmental concerns remain. 

3. Broader developmental assessment 

Professionals may explore areas such as: 

• communication 
• language 
• social interaction
• play 
• learning 
• movement 
• behaviour 
• sensory development 
• hearing 
• vision 

This can help distinguish between different developmental needs and identify support that may be useful. 

4. Referral where needed 

If autism or another developmental difference is suspected, a child may be referred to a paediatric, developmental or specialist autism service. 

In UK guidance, autism diagnostic teams include relevant multidisciplinary expertise, such as paediatrics, speech and language therapy and psychology. 

5. Further autism assessment 

A diagnostic assessment can include: 

• detailed developmental history 
• observation of the child 
• information from parents or carers 
• information from nursery or school where relevant 
• communication and developmental assessment 
• consideration of other possible explanations or coexisting needs 

No single autism test should determine the diagnosis. NICE specifically recommends using information from multiple sources and states that clinicians should not rely on an autism-specific diagnostic tool alone. 

6. Support planning 

Whether or not a child receives an autism diagnosis, an assessment may identify useful areas of support. 

The goal is to understand the child’s individual strengths, communication style and needs.

Early Support and Why It Matters 

Early autism detection is not about changing who a child is or trying to prevent autism. 

It is about understanding development sooner so that a child and family can access appropriate support where needed.

Support may include: 

Communication support 

A speech and language professional may help a child develop effective ways to communicate, whether through speech, gestures, visual communication, augmentative and alternative communication (AAC), or a combination of approaches. 

Educational support 

Nursery and school staff may adapt communication, learning environments, transitions or teaching approaches to match the child’s needs. 

Developmental support 

Children may benefit from support targeting everyday developmental skills, play, learning, emotional regulation or independence. 

Occupational support 

Where appropriate, occupational therapists may help with sensory needs, daily activities, motor skills or participation in everyday routines. 

Family resources 

Understanding why a child reacts or communicates in a particular way can help families make routines and environments more supportive. 

Needs-based support does not need to be framed around making a child appear “less autistic”. The aim should be participation, communication, comfort, development and quality of life. 

Early identification also does not mean that every developmental difference requires therapy. Support should be individualised to the child’s needs. 

Developmental Screening Is Not the Same as Diagnosis

This distinction is particularly important for parents using online developmental checklists.

Developmental monitoring 

This means observing how a child develops over time. 

Parents, healthcare professionals, nursery staff and teachers may all notice developmental changes. 

Developmental screening

Screening involves a more structured tool designed to identify whether further assessment may be useful. 

Autism diagnostic assessment 

Diagnosis requires a much broader evaluation of a child’s developmental history and current pattern of social communication and behaviour. 

Screening can help identify a reason to investigate further, but it cannot establish an autism diagnosis. 

In the United States, the American Academy of Pediatrics recommends autism-specific screening at 18 and 24 months. Healthcare pathways differ between countries, however, and parents should follow local guidance rather than waiting for a particular screening appointment if they already have concerns. 

A Final Note for Parents 

Searching for the early signs of autism can be emotionally difficult, particularly when every behaviour starts to feel significant. 

Try to look at your child’s development as a whole rather than focusing on one moment, one milestone or one comparison with another child. 

Children develop differently. 

One developmental difference does not mean autism. 

Having good eye contact does not rule autism out. 

A speech delay does not automatically mean autism. 

And an autism screening result is not a diagnosis. 

If something about your child’s development continues to concern you, it is reasonable to ask for professional guidance. You do not need to diagnose the situation yourself before starting that conversation. 

A qualified professional can help you look at your child’s communication, play, social development, sensory experiences and overall developmental pattern — and decide together whether further assessment or support would be useful. 

Frequently Asked Questions 

Evidence Basis 

This article was developed using current guidance and developmental information from authoritative health sources, including: 

• NHS: signs of autism in children and guidance on seeking assessment.
• NICE CG128: recognition, referral and diagnosis of autism in children and young people. 
• CDC Learn the Signs. Act Early: developmental milestones for 12 months, 18 months, age 2 and age 3. 
• CDC autism screening guidance: distinction between developmental monitoring, screening and diagnosis. 
• American Academy of Pediatrics / HealthyChildren: paediatric developmental and autism screening guidance. 

This information is educational and is not a substitute for individual medical or developmental assessment.