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Early Signs of Autism: ASD Symptoms in Babies and Young Children

January 2, 2024

Did you know autism spectrum disorder (ASD) can be detected in babies, infants, and toddlers, yet many children on the spectrum do not receive a diagnosis until the age of two or three? Because of that, it’s crucial to understand some of the early signs of autism in children.

This article overviews the main symptoms, characteristics, and signs of autism in children, helping more parents and caregivers get an early diagnosis for their little ones. Early intervention is the key to a healthy future for your child, so let’s learn all about it.

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Diagnosing Children with Autism Spectrum Disorder (ASD)

The National Institute of Neurological Disorders and Stroke (NINDS) cites four major “classic” symptoms that pediatricians often use to diagnose children with autism:

However, many of the above are almost impossible to see in a small baby who is not yet in the age range of talking or developing interests. This means many parents do not seek diagnosis until a later stage, and their child might miss out on the benefits of early intervention.

So, what signs are visible? Let’s break down some of the things that parents can look out for.

Signs of Autism in Babies

Every baby with autism spectrum disorder will display unique symptoms. However, several key traits may point to autism, depending on the age of your little one.

Signs of Autism in Infants 1 to 3 Months Old

Although the first three months of a child’s life may be too early to make a correct diagnosis of autism, there are some hints to look out for. The earliest signs of autism in infants 1 to 3 months old include:

  • Limited engagement with caretakers – babies may not respond to social cues like cooing or gestures such as waving and clapping.
  • Reduced eye contact – babies may avoid eye contact during activities like nursing and may be fussier and harder to comfort than neurotypical infants.
  • Sensory challenges – babies on the spectrum may experience distress from certain textures and sensory overload from noisy or flashing toys.

Signs of Autism at 4 to 6 Months

It can be challenging to diagnose autism at 4 to 6 months formally, but some early signs may become more evident at this stage of development. The potential signs of autism in babies 4 to 6 months old are:

  • Limited eye contact – a lack of consistent eye contact during interactions with caregivers.
  • Difficulty in social engagement – infrequent smiling or responsiveness to social cues like cooing and facial expressions.
  • Delayed or absent babbling
  • Limited interest in surroundings – reduced curiosity about the environment, people, or objects around them.
  • Sensory sensitivities – heightened sensitivity or aversion to certain textures, sounds, or lights.
  • Lack of motor movements – babies may not hold on or grasp onto objects.

Signs of Autism at 7 to 12 Months

During the period of 7 to 12 months, certain signs may indicate the possibility of autism in infants. If you notice any delays in your child’s development, it’s best to consult your doctor.

Some early signs of autism in babies 7 to 12 months old are:

  • Delayed crawling – some babies with autism may delay their crawling compared to their neurotypical peers.
  • Appearing unbalanced – some infants with autism may appear unbalanced or struggle with standing, even with support.
  • Avoidance of eye contact – limited or avoiding eye contact during interactions with caregivers or others.
  • Limited pointing – difficulty or absence in pointing to objects or pictures to express interest or communicate.
  • Speech development challenges – limited or incomprehensible speech may be observed, with the child not reaching typical speech milestones.
  • Lack of gestures – babies with autism may refrain from using gestures such as waving or shaking their heads for communication.

Signs of Autism in Toddlers

Toddlers with autism generally exhibit a progression of the symptoms expressed during infancy. Autistic toddlers may express frustration via tantrums or outbursts.

Diagnosing autism in toddler boys is markedly more common than in girls. At this stage, children often begin to show symptoms associated with autism.

Signs of Autism in 1-Year-Olds

Identifying signs of autism in 1-year-olds can be crucial for early intervention and support. Still, It’s important to remember that developmental timelines vary, and these signs alone do not confirm a diagnosis. 

Let’s explore some of the most common signs of autism in 1-year-olds.

Social interaction and communication challenges

  • They avoid eye contact – they may not look at their parents when they want something or look back at them when something exciting happens.
  • They don’t point or hold up objects – they may not point to things that excite them to make sure their parents see them, too.
  • They don’t respond to their parents when they call their name.
  • They don’t use gestures typical for their age – for example, they may not wave bye-bye without someone asking them to.
  • They may not smile back at people who smile at them.
  • They may not copy their parent’s actions, such as pretending to wash their hands when their parents are doing so.
  • They’re not pretending to have a conversation with their parents or babbling at all.
  • They struggle to understand simple instructions, such as “Show me the car.”

Challenges in playtime

  • They rarely show interest in playing with other children and don’t try to get their attention.
  • They don’t initiate games, such as peekaboo or chase. 
  • They don’t engage in pretend play, such as pretending to feed a baby.

Behavioral challenges

  • They show intense interest in certain toys and objects.
  • They engage in repetitive behaviors, such as spinning the wheels of a toy car constantly.
  • They show certain routines during playtime, such as lining up objects.
  • They show intense interest in certain activities and overreact when they cannot engage in them, such as watching their favorite cartoon.
  • They are upset by changes in routine; for example, their parents always have to follow the same route to their grandparents’ house.
  • They engage in repetitive body movement, such as flapping their hands, toe walking, arching their backs, and more.
  • They are sensitive to their environment and easily upset by bright lights, loud noises, or strong smells.

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Signs of Autism from 1 to 2 Years Old

Understanding and addressing signs of autism in the 1 to 2-year-old age range is exceptionally crucial for early intervention. The significance lies in the potential to provide timely support and interventions that can positively impact a child’s development. 

Let’s explore the most common signs of autism from 18 months until 2 years.

Challenges in communication and interactions

  • They are completely avoiding eye contact when someone is speaking to them or when they’re speaking to their parents.
  • They barely use sounds or gestures, or have limited to no speech.
  • They show little to no attention-seeking behavior – they are not pointing to objects or seeking approval for things they do.
  • They prefer to play alone and usually engage in solitary activities.
  • They don’t respond to social cues – they rarely respond to their parent’s smile or any kind of body language.
  • They don’t respond to their name.
  • They prefer having a routine and may throw a tantrum when they notice any changes, such as weekends or staying up past their bedtime.
  • They don’t understand socially acceptable and unacceptable behavior, such as approaching people without saying anything.
  • They gravitate towards their favorite people and refuse to leave their side at social gatherings.

Challenges during playtime

  • They’re not showing any interest in pretend play that’s typical for their age, such as playing with babies.
  • They’re not interested in playing with other children, or they awkwardly approach them without saying anything.
  • They have no sense of personal space when playing with other kids or may take another child’s toy without permission.

Challenges in behavior

  • They engage in repetitive behavior (stimming), such as finger flicking, flapping their hands, or rocking and swaying.
  • They struggle with listening to their parents or following where they’re pointing.
  • They have special interests that seem obsessive, such as collecting objects.
  • Have favorite objects they must use, such as a specific cup or plate to eat from.
  • They show signs of visual fixations, such as stare spells.
  • They show more interest in objects than people.
  • They have unusual sensitivity or reactions to sounds, sights, or textures, like covering their ears at loud noises or avoiding certain textures.

Signs of Autism in Children 3 to 5 Years Old

Autism spectrum disorder (ASD) is typically diagnosed more frequently after the age of 3, as signs of autism become more evident. However, there are instances where identification can occur earlier. Intervening at an early stage can contribute positively to a child’s development.

Signs of Autism in 3-Year-Olds

By the age of three, most children on the spectrum start showing clear symptoms of autism.  Signs of autism in 3-year-olds include challenges in:

Social and Communication Skills

  • They may prefer to play alone and have no interest in socializing with other children.
  • They don’t share their toys and get upset when other children play with them.
  • They do not understand turn-taking or pretend play.
  • They rarely initiate play. When they do, they often take other children’s toys or approach them without saying anything.
  • They are showing signs of language delays or regression in speech – they may not talk as much as their peers or not talk at all.
  • They’re avoiding eye contact with their parents, peers, or strangers.
  • They don’t who any facial expressions or imitate their parents when they do.
  • They repeat what others say rather than engage in a conversation.
  • They engage in “echolalia” – use words, phrases, or sounds repeatedly.
  • They may use wrong pronouns – for example, they may say “you” instead of “I” and vice versa.
  • They rarely use gestures, even when their parents ask them to, such as pointing, clapping, or waving goodbye.
  • They do not understand teasing or age-appropriate humor.
  • They avoid physical contact and overreact to their parents or family members trying to hug them or pat their heads.
  • They struggle with expressing their feelings or understanding their parent’s feelings, such as anger, sadness, or concern.


  • They engage in repetitive behavior, such as flapping their hands repeatedly or rocking back and forth.
  • They enjoy the sensation of spinning around or swaying.
  • They are fascinated with a particular toy or activity, often showing obsessive interests.
  • They follow a certain pattern when playing, often lining things up in a structured manner or piling toys.
  • They have a short attention span and may not show interest in things that require their focus.
  • They may seem hyperactive in certain situations or not react at all when they’re supposed to.
  • They insist on specific routines and may overreact when their routines change in any way, such as no daycare during the weekends.
  • They may engage in aggressive behavior when their routines are disrupted, sometimes even hitting their parents.
  • They may engage in self-harming behaviors, such as biting, head banging, or hitting.
  • They have unusual eating habits and engage in picky eating.
  • They have intense reactions to sounds, colors, tastes, or smells that cause them discomfort and pain.

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Signs of Autism in 4-Year-Olds

As child grows older, the signs of autism become more evident. It is crucial to promptly assess signs of autism in 4-year-old children. The sooner a child gets support, the easier it is to help with their development.

Common signs of autism at this age include:

Challenges in Social Skills

  • They don’t respond to their name.
  • They avoid eye contact with their parents, peers, teachers, or strangers who talk to them.
  • They may prefer to play alone and have intense reactions when other children try to play with them.
  • They struggle to share with other children and don’t understand turn-taking.
  • They may not understand pretend play and prefer to play with real objects – for example, they’d rather use real food than play with plastic.
  • They may not share stories with their parents or talk about the things that happen to them.
  • They have no interest in socializing with other children their age or interacting with them in any way.
  • They actively avoid physical contact and have intense reactions to it.
  • They have little to no friends and show no interest in making friends.
  • They rarely make facial expressions or make ones inappropriate for certain situations.
  • They cannot be easily comforted and prefer to be left alone.
  • They struggle with understanding other people’s emotions and may not show high levels of empathy.
  • They struggle with talking about the way they feel or express their emotions in the right way.

Challenges in Language and Communication Skills

  • They struggle with forming sentences – by the age of 4, children typically talk smoothly with other people being able to understand them.
  • They repeat words or phrases – by age 4, most children no longer repeat after their parents and start forming their own sentences.
  • They respond inappropriately to questions or directions, such as not staying on topic in the conversations.
  • They are unable to describe their feelings or say what they’re thinking, which is normal for preschoolers their age.
  • They are not interested in telling stories or talking about their experiences with their parents.
  • They rarely use body language or gestures to communicate.
  • They use reversing pronouns – for example, they say “you” instead of “I”; by the age of 4, most children learn pronouns and use them as part of their speech.
  • They struggle to understand jokes appropriate for their age – by the age of 4, most children understand simple jokes and the mechanics of joke telling.

Challenges in Their Behaviors

  • They organize their toys and objects in a repetitive manner, which may give them a sense of comfort of predictability.
  • They always play with toys in the same way, which could be an early sign of a preference for predictability.
  • They are upset by small changes in their daily routines, and any disruptions lead to highly emotional reactions.
  • They perform repetitive movements – for example, they engage in hand-flapping or rocking as a form of self-soothing when anxious or scared.
  • They insist on specific routines – children with autism often rely on a set of rituals or routines to navigate their daily lives.
  • They dedicate extensive time and attention to things they’re fixated on, such a particular toy, a TV show, or an activity they enjoy.
  • They display signs of impulsive behavior and act without considering potential consequences.
  • They struggle to maintain focus on tasks or activities and may exhibit restlessness.
  • They engage in aggressive behavior, such as hitting or biting, especially when having difficulty expressing their needs and emotions.
  • They may overreact to sensory stimulation, such as sounds, textures, lights, or smells.

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Signs of Autism in 5-Year-Olds

Most children on the spectrum get diagnosed by the age of 5. However, even if a child hasn’t been diagnosed yet, the symptoms become more evident as they start kindergarten or don’t reach their developmental milestones.

Common signs of autism in 5-year-olds include:

Challenges in Interacting With Their Peers and Others

  • They may show a preference for solitary play – most 5-year-old children engage in playtime with their peers.
  • They struggle to understand pretend play with their peers and create stories and scenarios together.
  • They struggle to understand the concept of personal space – for example, they may stand too close to others and not understand when someone needs space.
  • They may not consistently respond to their name, appearing inattentive or unresponsive in social situations.
  • They may find eye contact uncomfortable and avoid it during social interactions.
  • They may not be interested in forming friendships and prefer independent activities.

Behavioral Challenges

  • They haven’t outgrown their repetitive behaviors and often engage in stimming behaviors, such as hand flapping, rocking back and forth, and more.
  • They’re displaying intense reactions to changes in routine – for example, the holidays may cause them distress and emotional dysregulation.
  • They may actively avoid physical contact – for example, while most 5-year-olds enjoy physical affection from their caregivers and peers, neurotypical children often display discomfort with hugs or touch.
  • They may develop intense interests in specific topics or objects, showing a deep focus that surpasses typical curiosity.
  • They may struggle to maintain focus in situations that don’t align with their specific interests.
  • They may show signs of heightened irritability and aggression, especially when unable to express their emotions verbally.
  • They may display signs of hyperactivity and struggle with impulse control.
  • They lack a sense of fear and engage in activities that pose risks without understanding the danger they bring.

Challenges in Language and Communication

  • They may use incorrect grammar, which is unusual for 5-year-olds, and struggle with language development.
  • They may excessively talk about specific topics or show a limited interest in talking with their peers.
  • They haven’t outgrown their repetitive language stage and persistently repeat words or phrases.
  • They struggle with understanding and using body language in communication.
  • They struggle with forming concise sentences, which leads to difficulties in communication.
  • They may not seek approval from their parents or teachers and show a limited response to emotional reactions from them.

Do Signs of Autism in Children Differ in Girls and Boys?

Early signs of autism are sometimes clearer in boys than in girls. According to research, only one in four children diagnosed with autism is female.

Only one girl in every nine boys is diagnosed with Asperger’s syndrome. Young children might be misdiagnosed as having social communication disorders or developmental disorders.

These girls are often labeled as having developmental delays, but without the diagnosis of autism, their access to resources and care becomes limited.

The Cleveland Clinic recommends being proactive and seeing your pediatrician if you notice any signs your daughter might be autistic, especially if she is between regular medical check-ups.

A chart of early sings of autism in infants and children

When Can My Child Be Diagnosed with Autism?

According to the Center for Disease Control (CDC), doctors can diagnose autism at 18 months or earlier, with screenings occurring during wellness checkups at:

  • nine months,
  • 18 months,
  • 2 years, and
  • 3 years.

Many children receive an official diagnosis around the age of two or three, often after starting school when challenges in social skills become evident. It’s never too late to seek a diagnosis and access resources for easier life management with autism.

If your doctor is unsure if a diagnosis of autism is appropriate for your infant, the CDC recommends seeking a second opinion. The earliest interventions can serve as building blocks for your child’s future therapies, and change your child’s developmental path.

The CDC cites that, in the first three years of a child’s life, children are more likely to change undesirable habits and adopt positive ones. They suggest trying several interventions until you find one (and a therapist) your child responds to best.

Early Interventions for Autism

Once you’ve spotted the signs of autism and received an early diagnosis, you can consider the next steps. Psychiatrists, psychologists, and occupational therapists can all help support autistic children. 

Here are the most popular early interventions and therapies:

  • Early Start Denver Model: ESDM is a relationship-based program that encourages positive feedback, shared activities, and parental involvement.
  • Applied Behavioral Analysis: Many families use ABA, which encourages a positive reward system and parental engagement with the program.
  • Picture Exchange Communication System: PECS teaches non-verbal and semi-verbal children to communicate via pictures and symbols.
  • Verbal Behavioral Intervention: VBI is also used with children who struggle with speech, but instead of communicating with pictures, it focuses on teaching verbal communication.
  • Discrete Trial Training and Pivotal Response Training: DTT and PRT focus on behavioral and motivational challenges a toddler with autism may experience.
  • DIR/Floortime Therapy: DIR/Floortime aims to help children with ASD connect while using their interests and passions to develop engagement skills and symbolic thinking, increase logical thinking, and improve interaction.

Timely Intervention is the Key

While autism is most often diagnosed when a young child hasn’t met popular milestones during the formative years and/or when a child’s development has suddenly regressed, some experts believe there are signs of autism that point toward a diagnosis earlier in a child’s life.

While not every person who is autistic can be diagnosed as an infant, there are many benefits to receiving a diagnosis before preschool age.

If your child is exhibiting signs of autism, even minor ones, document them and share your concerns with your child’s physician. The earlier a child with autism is diagnosed, the sooner families and specialists can work with the child using popular interventions and selected therapies.

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Q: How early can you see signs of autism?

A: Signs of autism can be noticed as early as 12 to 18 months, but a formal diagnosis is typically made after age 3. Early detection during the first few years allows for more effective intervention and support.

Q: What are early signs of autism in babies?

A: Early signs of autism in babies may include limited eye contact, difficulty with social interaction like not smiling back, and delays in reaching developmental milestones such as babbling and engaging in imaginative play. Additionally, sensory processing challenges, repetitive movements, and a lack of response to their name can be early indicators.

Q: Can autism be outgrown? 

A: Autism is a lifelong condition. However, early intervention and therapy can significantly improve a child’s skills and lead to a better quality of life.

Q: What is the biggest symptom of autism?

A: The primary symptom of autism is often characterized by challenges in social communication and interaction, coupled with engaging in restricted or repetitive behaviors and interests.


Developmental milestones in toddlers with autistic disorder, pervasive developmental disorder—not otherwise specified and atypical development

How different are girls and boys above and below the diagnostic threshold for autism spectrum disorders?

Finding the True Number of Females with Autistic Spectrum Disorder by Estimating the Biases in Initial Recognition and Clinical Diagnosis

Early Intervention for Autism

What are the treatments for autism?

DIR/Floor Time in Engaging Autism: A Systematic Review

What is the Picture Exchange Communication System or PECS?

Early Start Denver Model (ESDM)

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