Autistic Children and Developmental Milestones

A developmental milestone is a sign of typical child development. Children reach dozens of developmental milestones between birth and adulthood. Early milestones include social smiles, rolling over, and sitting up. Later milestones involve the acquisition of language, social, physical, and emotional skills, and intellectual abilities.

Children with autism tend not to reach all of their developmental milestones at the appropriate times. But that statement is a huge oversimplification of the reality because:

  • Many autistic children reach early developmental milestones on time or early, but then lose ground.
  • Most autistic children reach some of their developmental milestones on time or early, but reach others late or not at all.
  • Some autistic children reach some of their developmental milestones extraordinarily early but reach others extraordinarily late.
  • Children with autism can appear to gain important skills—but in fact, be unable to use those skills in real-world situations.
  • Many children with autism have so-called "splinter" skills, which can be very advanced but which are not useful in daily life.
  • Autistic children, particularly girls who are high-functioning, are sometimes able to hide or overcome some developmental delays.

With so few absolutes, it's no wonder both parents and practitioners can find it hard to spot autism, especially in very young or very high functioning children. There are, however, a few developmental markers that are most likely and most obvious when a child is autistic.

Child playing with blocks
Alita Ong / Stocksy United

What Are the Developmental Milestones?

The 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 described, they also suggest that parents keep an eye out to be sure their child is at or close to normal.

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

  • Copies adults and friends 
  • Shows affection for friends without prompting
  • Takes turns in games
  • Shows concern for crying friend
  • Understands the idea of “mine” and “his” or “hers”
  • Shows a wide range of emotions
  • Separates easily from mom and dad
  • May get upset with major changes in routine
  • Dresses and undresses self


  • Follows instructions with 2 or 3 steps
  • Can name most familiar things
  • Understands words like “in,” “on,” and “under”
  • Says first name, age, and sex
  • Names a friend
  • Says words like “I,” “me,” “we,” and “you” and some plurals (cars, dogs, cats)
  • Talks well enough for strangers to understand most of the time
  • Carries on a conversation using 2 to 3 sentences

Cognitive (learning, thinking, problem-solving)

  • Can work toys with buttons, levers, and moving parts
  • Plays make-believe with dolls, animals, and people
  • Completes puzzles with 3 or 4 pieces
  • Understands what “two” means
  • Copies a circle with pencil or crayon
  • Turns book pages one at a time
  • Builds towers of more than 6 blocks
  • Screws and unscrews jar lids or turns door handles

Movement/Physical Development

  • Climbs well
  • Runs easily
  • Pedals a tricycle (3-wheel bike)
  • Walks up and down stairs, one foot on each step

When Missing Developmental Milestones May Suggest Autism

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.

So when should parents be concerned about autism? CDC provides a shortlist of issues that should raise red flags.

While these issues can be signs of autism, however, they may not be. 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.

Why Monitoring Developmental Milestones for Autism 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 idiosyncratically, or actually regress. Because of these issues, it can be tough to spot autism just by watching for missed developmental milestones.

How Autistic Delays Can Be Masked or Hidden

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 autistic children have few or mild delays, challenges, or stims. 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):

  • GirlsAutism 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 culturally appropriate for 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 skillsQuite 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 wonderful children take it upon themselves to learn to understand their autistic peer and to 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 him or herself.
  • 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 as being "chips off the old block." It can be especially hard for these parents to see their child labeled autistic, as the label could easily apply to them as well.

What Parents Should Do

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

If your intuition was incorrect, you've lost nothing but an hour of time and a load of anxiety. If your child does, indeed, have developmental delays you've taken action promptly and can expect to quickly access resources and programs that can help him or her to overcome any challenges.

Bottom line, you have nothing to lose and everything to gain by taking prompt action!

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. Matson JL, Mahan S, Kozlowski AM, Shoemaker M. Developmental milestones in toddlers with autistic disorder, pervasive developmental disorder--not otherwise specified and atypical development. Dev Neurorehabil. 2010;13(4):239-47. doi:10.3109/17518423.2010.481299

  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.