Search IconSearch

How Common Is Autism?

Current research suggests 1 out of every 36 children in the U.S. has ASD — and that’s probably an undercount

Happy child sitting on stool in healthcare office, with toys around

The clinical term for autism is autism spectrum disorder (ASD). It’s a neurodevelopmental disorder — a condition you’re born with. Basically, changes in the brain cause people with autism to learn, behave, communicate or interact differently from their neurotypical counterparts.


Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

“It really is a spectrum,” says developmental pediatrician Carrie Cuffman, MD. “No two people with autism are alike.” Some autistic individuals’ symptoms are barely noticeable, while others are severely impaired by them. That diversity of experience makes identifying the condition tricky, to say the least.

Even so, ASD diagnoses are on the rise. Dr. Cuffman explains why.

Why have autism diagnoses increased?

Autism diagnoses have been climbing consistently over the past 20 years, both in the U.S. and around the globe.

The most recent data from the U.S. Centers for Disease Control and Prevention (CDC) underscore how common autism is. They report that 1 in every 36 children has ASD. They broke it down by sex, too. Their estimate: approximately 4% of boys and 1% of girls are autistic. (Unfortunately, they didn’t collect data regarding gender identity, so we have no insight into ASD prevalence on that score.)

That’s a pronounced increase, but it’s not a sign of an “autism epidemic.” While it’s possible that there’s been a slight increase in the number of people who have the condition, most of that growth can be explained by changes in ASD diagnosis and treatment.

Awareness and accommodations

In many respects, the rise in ASD diagnoses over the past few decades is good news. It’s a sign that awareness of the condition has gone up.

“You’re much more likely to bring your kid into your provider and ask about autism when you know what it is,” Dr. Cuffman explains, “So we’re diagnosing more kids — and doing it earlier than we used to.” And children aren’t the only ones benefitting. Many individuals who reached adulthood without ever being worked up for the condition are finally getting diagnoses, decades later.

But it’s not just public awareness (and acceptance) that’s fueling the rise in diagnoses: It’s also the fact that an ASD diagnosis may actually help children now, in ways it didn’t in previous generations.

“Another explanation for the increasing numbers is that more services are available,” Dr. Cuffman adds. “It's worth getting your kid diagnosed now because there are more treatment options out there that you can access.” We’re talking speech and language therapy. Social skills groups. Specialists in developmental nutrition and psychiatry. Simply put: There’s a wide range of supportive services out there to help autistic children thrive. Many of these services either didn’t exist or weren’t accessible in previous decades.

“Parents wouldn’t bother to have their kids evaluated if there weren’t accessible treatments,” she notes. “Now, having a diagnosis means you’re more likely to get help for your child.”


Changes to the diagnostic criteria

The rise in ASD cases isn’t entirely the result of the growing understanding of the condition or the incentive to get a formal diagnosis. The numbers also went up because what counts as ASD has changed over time.

2013 saw the publication of the 5th edition of the Diagnostic and Statistical Manual (DSM-5) — the American Psychiatric Association’s (APA) reference text. This book classifies and sets out all of the diagnostic criteria for mental health and brain-related conditions.

Before 2013, ASD didn’t exist. Instead, there were several developmental disorders in the DSM that had similar characteristics:

It was, in a word, confusing. The diagnoses were mutually exclusive, meaning that if a child had some — but not all — of the symptoms for several of these conditions, the provider needed to choose the diagnosis that best fit the child. The same was true of attention-deficit/hyperactivity disorder (ADHD). It used to be the case that you couldn’t diagnose somebody with ASD and ADHD.

The result: Providers mis- or undiagnosed lots of children. The diagnostic criteria had a particularly negative impact on girls, kids with mild symptoms and kids with other, more obvious intellectual disabilities.

In 2013, the APA changed its framing.


“All of these conditions now fall under the umbrella of autism spectrum disorder,” Dr. Cuffman explains. In other words, those four diagnoses no longer exist. The diagnostic criteria for ASD being as expansive as it is means fewer children fall through the cracks. It also means that the number of people who qualified as autistic grew overnight.

In thinking about the changing clinical standards, there are a few things to keep in mind:

  • Many people who grew up with the older diagnoses still identify with that terminology. For example, some people who were originally diagnosed with Asperger’s — while now classified as having ASD — still refer to themselves as “aspies.”
  • The DSM-5 is a reference text for mental health professionals practicing in the U.S., but providers around the world use it, too (it’s available in 18 different languages). Still, depending on the country, people living outside the U.S. may not use the same terminology or diagnostic criteria.

Other reasons ASD is on the rise

The vast majority of the increase in ASD cases can be explained by the changing diagnosis and growing public awareness of the condition. But Dr. Cuffman and other researchers concede that there may be at least some real-world increase. If there is, it’s likely due to a combination of factors like:

Genetic factors

Unlike conditions like Down syndrome, which are the result of a single, specific genetic difference, there are over 1,000 potential genetic changes that can result in ASD.

Autism can also be hereditary. That matters because more autistic people than ever before are getting the support they need at a young age. Those early interventions can have a big impact on quality of life and make it easier to have relationships — and children — as adults.

Environmental exposure

“It’s clear that toxic insults to the health of a fetus or newborn are big risk factors for autism,” Dr. Cuffman notes. That exposure may happen in utero or shortly after birth. Here are a few examples:

  • Issues with oxygenation (the fetus not getting enough air).
  • The birthing parent having an infection.
  • Exposure to toxic substances like alcohol, opioids or thalidomide.
  • Interacting with polluted air, water or soil.

Modern medicine

There are certain variables that researchers say raise your likelihood of having autism. A lot of them have to do with the circumstances of a child’s birth. ASD is more common when one or more of the following are true:

  • Maternal age is over 35.
  • Paternal age is over 40.
  • A baby is preterm.
  • A pregnancy has significant complications.
  • The child’s birth weight is low.

You may be noticing a pattern here: Medical advances mean that children who may not have survived in the past are alive and well today. The result is an increase in the prevalence of neurodevelopmental disorders.

Don’t blame vaccines

There’s one thing we know for sure isn’t causing the increase in ASD: vaccines. In 1998, a doctor and anti-vaccination activist named Andrew Wakefield published a now-discredited paper in The Lancet. In it, he claimed that the MMR vaccine caused autism. It turned out that the paper was fraudulent and that Wakefield manipulated his research findings for financial gain. The Lancet retracted the paper and Wakefield lost his medical license.


“The Wakefield study was a total lie, but it made its way into the public eye,” Dr. Cuffman laments. It’s one of several misconceptions about the increasing prevalence of autism.

We’re probably still undercounting

Autism prevalence has been steadily increasing over the past few decades for many different reasons, like changes to the diagnostic criteria, increased public awareness of the condition and more equitable access to healthcare, testing and treatment. But that doesn’t mean the number we have today is necessarily accurate either.

The CDC determines autism prevalence by looking at the school and medical records of all the children living in a certain area. They then compare those numbers with data from other areas. Not only does that miss children who don’t have school or medical records, but it also doesn’t control for social determinants of health. For example, the raw data suggests that autism rates vary significantly by state, which doesn’t make sense. What those numbers actually reveal is the fact that some states are undercounting (and underserving) their autistic population.

That suggests autism prevalence is probably higher than the 1 in 36 statistic we’re working from right now.

As awareness continues to rise — and healthcare and support services become more accessible — we can expect the numbers to continue trending upward. And that’s a good thing because it means more people are getting the care they deserve.


Learn more about our editorial process.

Related Articles

Child talking with caregiver on couch
July 12, 2024/Mental Health
Talking To Your Child About School Shooting Drills

‘Active shooter’ exercises may raise both awareness and anxiety

Child crying and screaming, with caregiver handing over a lollipop, with another caregiver with hands on head, stressed
June 27, 2024/Children's Health
How To Deal With Toddler Tantrums: Tips From an Expert

Stay calm, don’t give in and try to refocus their attention

Parent with teen live action role playing in community park, with people walking dogs in background
June 26, 2024/Children's Health
Building Resiliency: 6 Ways To Boost Your Teen’s Confidence and Coping Skills

Integrating coping skills into your teen’s daily routine helps turn self-care into a lifelong healthy habit

Caregiver kneeled down, talking with child in front of school
June 25, 2024/Children's Health
Have an Aggressive Toddler? Here’s How To Manage Their Behavior

Tantrums and meltdowns are normal, but you can help your child manage their bigger emotions

Adult in the passenger seat of car while smiling teen drives
June 19, 2024/Children's Health
Teen Not Talking? Here’s How To Break the Silence

Talking in the car, resisting the urge to judge and asking specific questions can help rebuild rapport

Baby getting nasal irrigation
June 17, 2024/Children's Health
Neti Pot for Babies: Is Nasal Irrigation Safe?

Yes, it’s safe for babies starting at about 9 months old and can help clear nasal mucus

Rainbow-colored heart hovering above healthcare provider's hand, with child sitting in exam chair
June 12, 2024/Parenting
How To Find an LGBTQIA-Friendly Pediatrician for Your Child

Local LGBT centers, online directories, visual cues and gender-affirming care or non-discrimination policies can all be helpful resources and cues

Smiling parent holding smiling baby in a pool
June 7, 2024/Children's Health
When Can Babies Go in the Pool?

Wait until they’re at least 6 months old before your little one takes their first dunk

Trending Topics

Female and friend jogging outside
How To Increase Your Metabolism for Weight Loss

Focus on your body’s metabolic set point by eating healthy foods, making exercise a part of your routine and reducing stress

stovetop with stainless steel cookware and glassware
5 Ways Forever Chemicals (PFAS) May Affect Your Health

PFAS chemicals may make life easier — but they aren’t always so easy on the human body

jar of rice water and brush, with rice scattered around table
Could Rice Water Be the Secret To Healthier Hair?

While there’s little risk in trying this hair care treatment, there isn’t much science to back up the claims