Autism and Developmental Delays

Are missed milestones a sign of a spectrum disorder?

Children with autism spectrum disorder (ASD) often have developmental delays, meaning they do not to reach all of their social, emotional, communication, cognitive, and physical milestones at the appropriate times. But that statement is a huge oversimplification for several reasons.

Most autistic children reach some of their developmental milestones on time or early—sometimes extraordinarily so—but reach others late, very late, or not at all. Many also end up losing ground over time.

Child playing with blocks
Alita Ong / Stocksy United

Children with autism can appear to gain important skills but be unable to use them in real-world situations. Many have so-called "splinter" skills, which can be very advanced but not useful in daily life.

Autistic children, particularly girls who are high-functioning, are sometimes able to hide or overcome some developmental delays, which can make using milestones as a prompt for diagnosis difficult.

This article discusses a few developmental markers that are most likely and most obvious when a child has autism. While there are few absolutes when it comes to this, this may help you gauge your child's development and know what to bring to their healthcare provider's attention.

What Are the Developmental Milestones?

The Centers for Disease Control and Prevention (CDC) divides developmental milestones into groups: movement/physical, cognitive, language/communication, social/emotional. They list specific levels of achievement for each age, starting with 1 month and moving through adolescence.

While they make it clear that children may not reach any given milestone at the precise age outlined, they also suggest that parents keep an eye out to be sure their child is at or close to what's expected.

Most children with autism are diagnosed at a relatively young age—often by the age of 3. Here is a simplified list of milestones for 3-year-olds from the CDC:

Social and Emotional

  • Calms down within 10 minutes after you leave
  • Notices other children and joins them to play


  • Says their first name when asked
  • Can have a conversation with at least two back-and-forth exchanges
  • Talks well enough for strangers to understand most of the time
  • Can ask “who,” “what,” “where,” or “why” questions
  • Names an action that is happening in a book or picture, such as "running" or "eating"

Cognitive (Learning, Thinking, Problem Solving)

  • Copies a circle with pencil or crayon
  • Avoids touching hot objects like a stove, when warned

Movement/Physical Development

  • Can feed themselves using a fork
  • Can string items like large beads or macaroni
  • Can put on certain clothes by themselves, such as a jacket or pants

Why Children Miss Developmental Milestones

There are many reasons why children miss developmental milestones. In most cases, there's no particular cause for concern.

That's because:

  • Children are different from one another and, naturally, develop at different rates.
  • Children who are born prematurely may miss milestones but usually catch up.
  • Boys are often slower to develop than girls, but almost always catch up.
  • Many children are so focused on certain milestones that they may miss others. For example, a very physically adept child may reach advanced physical milestones and then later catch up on social milestones.
  • Early medical challenges may slow development, but most children are able to catch up to their same-age peers.
  • Certain correctable challenges, such as difficulty with hearing, can slow early development but have little impact on long-term development once addressed.

With that said, there are times when developmental delays may indicate a concern such as autism.

When Developmental Delays May Suggest Autism

The CDC provides a list of issues that are considered early signs of autism, though they may also occur in those without a spectrum disorder.

Autism is more likely when children have more than one of these issues or have other related issues in the social/emotional or communication realms:

  • Can’t work simple toys (such as pegboards, simple puzzles, turning handles)
  • Doesn't respond to name by 9 months of age
  • Doesn't show facial expression (like being sad, angry, or happy) by 9 months of age
  • Uses few or no gestures (such as waving goodbye) by 12 months of age
  • Doesn’t play pretend or make-believe by 48 months of age
  • Doesn't play simple interactive games such as pat-a-cake by 12 months of age
  • Doesn't notice other children and join them in play by 36 months of age
  • Doesn’t make eye contact
  • Doesn't notice when others are upset or hurt by 24 months of age
  • Does not share interests with others by 15 months of age
  • Shows restricted or repetitive behaviors or interests
  • Does not sing, dance, or act for you by 60 months of age
  • Loses skills they once had

Why Monitoring for Autism This Way Can Be Misleading

Sometimes, children with autism miss multiple milestones and have clear and obvious developmental delays. Often, however, missed milestones can be masked or even invisible.

This is because children with autism aren't simply delayed; they learn and behave differently from their typical peers.

In addition, autism is rarely obvious from birth. Many children with autism develop normally for a period of time and then either slow down, develop in small ways, or actually regress.

Because of this, it can be tough to spot autism just by watching for missed developmental milestones.

Masked or Hidden Delays in Autism

Some children with autism have severe cognitive delays, behavioral challenges, or physical "stims" (rocking or flapping) that make it obvious that something is wrong. But many don't. When that's the case, developmental delays may be hard to spot.

Here are a few groups of children whose developmental delays may not be obvious until social, emotional, or communication demands increase (usually after grades 1 or 2):


Autism generally causes children to be quiet, socially withdrawn, and less likely to raise their hands or speak out. They may appear "dreamy" or inattentive.

These behaviors are social expectations of girls in most parts of the world. Thus, young autistic girls who are not meeting developmental milestones may slide under the radar. They are often labeled as "shy and quiet," and, perhaps, not terribly bright.

It may take quite a while for parents and teachers to notice other symptoms.

Children With Impressive Intelligence or Splinter Skills

Quite a few children with autism are very bright or have surprising skills that are far beyond their years.

For example, some children with autism can solve complex puzzles, read at a very young age, or show impressive math, music, or computer skills. They may also have advanced vocabularies in their areas of special interest.

When this is the case, parents and teachers may not notice that the same child who can solve complex math equations is unable to play imaginatively or catch a ball.

Children With Empathetic Siblings or Peers

In some families and classrooms, empathetic siblings or peers can actually mask another child's autism.

These children take it upon themselves to learn to understand their autistic peer and speak for them. While this is undoubtedly kind and caring, it's also a form of enabling that can make it hard to know what the autistic child really can do for themself.

Children of Parents With Autistic Traits

It's not unusual for children with autism to have parents who are either diagnosable with high-functioning autism or who have so-called "shadow" traits of autism.

When this is the case, parents may see their children as developing typically or just like them. Some parents may not want their child to be labeled as autistic because they struggle with the idea that the same could be said about them.

If Your Child Has Developmental Delays

If you think your child has developmental delays and may be autistic, take action. Ask your child's healthcare provider to screen for delays, with a special emphasis on social, communication, and emotional skills.

If your intuition was incorrect, you can put a potential diagnosis out of mind. If your child does, indeed, have developmental delays, you've taken prompt action to get to the bottom of why they are occurring and what can be done to help them overcome any challenges.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. CDC's developmental milestones.

  2. Centers for Disease Control and Prevention (CDC). Child development basics: healthy development.

  3. Centers for Disease Control and Prevention (CDC). Signs and symptoms of autism spectrum disorders.

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  5. Feige E, Mattingly R, Pitts T, Smith AF. Autism spectrum disorder: investigating predictive adaptive behavior skill deficits in young children. Rossignol D, ed. Autism Research and Treatment. 2021;2021:1-9. doi:10.1155/2021/8870461

  6. Rynkiewicz A, Schuller B, Marchi E, et al. An investigation of the 'female camouflage effect' in autism using a computerized ADOS-2 and a test of sex/gender differences. Mol Autism. 2016;7:10. doi:10.1186/s13229-016-0073-0

  7. Meilleur AA, Jelenic P, Mottron L. Prevalence of clinically and empirically defined talents and strengths in autismJ Autism Dev Disord. 2015;45(5):1354–1367. doi:10.1007/s10803-014-2296-2

  8. American Academy of Pediatrics. What are the early signs of autism?

By Lisa Jo Rudy
Lisa Jo Rudy, MDiv, is a writer, advocate, author, and consultant specializing in the field of autism.