Autism speech regression: what to do when your toddler loses words
If your toddler has stopped using words they used to say, call your pediatrician this week and ask for developmental screening and a hearing test. You do not need to wait and see.
Budding Futures ABA provides in-home ABA therapy across Colorado. We do not diagnose autism and we do not provide speech therapy. This guide quotes outside researchers and agencies by name and links every source.
The American Academy of Pediatrics says about 25% of children later diagnosed with autism "may develop some language that they suddenly or gradually stop using," typically between 15 and 24 months.
- Lost words are a reason to act now. The CDC's advice is to "act early" and ask for developmental screening.
- In Colorado, children under 3 go through Early Intervention Colorado. Ages 3 to 5 go through your school district's Child Find.
- A doctor will usually check hearing first, and may check for seizures or a genetic cause.
- Losing words does not settle how a child will do. A study of 408 children found regression "does not necessarily foreshadow worse developmental outcomes."
- Vaccines are not the cause. A 2014 analysis that included more than 1.2 million children found no link with autism.
Published October 7, 2026 by the Budding Futures team. The researchers and agencies quoted are outside sources. They are not affiliated with Budding Futures and did not review this page. This is general education, not medical advice. Lost skills are a reason to call your child's doctor.
What speech regression looks like in children with autism
Speech regression means a child had words and then stopped using them. Regression means a loss of previously acquired skills: words, gestures or social interaction a child already had. It can happen fast or slowly, and slow losses are easy to miss until you look back at old videos.
Signs of regression parents notice first: lost words, fewer sounds, less eye contact
The American Academy of Pediatrics describes it on its parent site: some children "may develop some language that they suddenly or gradually stop using." It adds: "They might also become more socially withdrawn. This change is called a regression in skills."
It is often more than words. In a study that watched babies over many visits, researchers at the UC Davis MIND Institute saw "declines in social communication" in 19 of 22 infants who were later diagnosed with autism (Ozonoff and colleagues, 2010). They tracked three things at 6, 12, 18, 24 and 36 months:
- How often the baby looked at faces.
- How often the baby smiled at people.
- How often the baby made sounds toward someone.
All three dropped over time in the children later diagnosed. For lost words in particular, ASHA lists "Loss of earlier learned words" among the signs that call for a closer look.
The age it usually shows up
Between 15 and 24 months, according to the AAP. A 2013 analysis that pooled 85 articles and 29,035 participants put the average at 1.78 years, which is about 21 months (Barger, Campbell and McDonough).
You may see the phrases regressive autism, autism regression or autistic regression online, and some sites write about children with regressive autism as a separate group. These are everyday terms, not a diagnosis. A doctor diagnoses autism spectrum disorder. Regression describes how the signs showed up.
What to do this week
A child losing skills is hard to watch, and parents and caregivers often second-guess what they saw. You do not have to work out the cause yourself. Your job this week is to write down what you see and get your child in front of the right people. These five steps come from the CDC, the AAP and Colorado's own program.
- Write down dates and film what you see. List the words your child used to say and when you last heard each one. Save old videos and take new ones. Memory alone misses a lot: in the UC Davis study, "most parents did not report a regression" even when repeated testing showed one (Ozonoff 2010).
- Call the pediatrician and ask for developmental screening. The CDC says: "If your child is not meeting one or more milestones, has lost skills he or she once had, or you have other concerns, act early. Talk with your child's doctor, share your concerns, and ask about developmental screening." Use the words "lost skills" on the call. The CDC defines developmental milestones as "things most children (75% or more) can do by a certain age," so a lost milestone is worth a call on its own.
- Ask for a hearing test. The AAP's language delay guide says a doctor may "Order a hearing test and refer you to a speech and language therapist for testing."
- Make the early intervention referral yourself. You do not have to wait for the doctor. The CDC: "Call your state or territory's early intervention program to find out if your child can get services to help." In Colorado, anyone can refer a child, including a parent (next section).
- Ask about autism screening. The AAP recommends autism screening for all children at the 18-month and 24-month checkups. If yours was skipped, ask for it now.
None of these steps needs Budding Futures, and none of them should wait for a therapy provider.
Who to call in Colorado
Under 3: Early Intervention Colorado
Early Intervention Colorado is the state program for infants and toddlers, run through the Colorado Department of Early Childhood. Its home page says it plainly: anyone can refer a family, including you. Start at eicolorado.org, where the current referral line and online form are posted.
We are not printing a phone number here. Numbers change, and we want you to read it on the state's own page.
Ages 3 to 5: Child Find
From the third birthday, evaluation moves to your school district. The process is called Child Find. Contact your district's Child Find or special education office and ask for an evaluation. Put the request in writing so there is a date on it. The Colorado Department of Education explains the steps in its family fact sheet.
If your child ends up with an Individualized Education Program, our guide to autism IEPs in Colorado covers what to ask for.
How fast the state has to act
| Your child's age | Who you contact | The clock | Where it is written |
|---|---|---|---|
| Under 3 | Early Intervention Colorado | Evaluation and the first plan meeting (called an IFSP) within 45 days of the referral. | Federal rule 34 CFR 303.310, titled "Post-referral timeline (45 days)." |
| 3 to 5 | Your school district (Child Find) | Evaluation finished within 60 days of your written consent. | Colorado Department of Education: "the school district must complete the evaluation in 60 days." Federal rule 34 CFR 300.301. |
A timelines page written for Early Intervention Colorado evaluation providers lists shorter targets inside the 45 days, including "Initial contact within seven (7) business days of Referral Date." We could not confirm who hosts that page, so treat it as a guide and not as a promise.
Causes of regression: what a doctor rules out first
Lost words have more than one possible cause. Sorting them out is a doctor's job, not a therapy provider's. Here is what the sources say gets checked.
Hearing
A hearing check comes early. ASHA explains why: "children with ASD are often initially suspected of having a hearing problem." It says screening includes "hearing screening to rule out hearing loss as a contributing factor to communication and behavior difficulties."
Seizures and Landau-Kleffner syndrome
Outside source, not affiliated with Budding FuturesLandau-Kleffner syndrome (LKS) is a rare nervous system disorder that begins in childhood. It is characterized by repeat seizures and a sudden or gradual inability to understand or express language (aphasia).
It is rare. The point is not that your child has it. The point is that a doctor may want to check for seizure activity with an EEG, a test of brain waves, before anyone settles on an explanation.
Genetic conditions such as Rett syndrome
Some genetic conditions involve losing skills. The National Library of Medicine describes Rett syndrome this way: babies "seem to grow and develop normally at first. Between 3 months and 3 years of age, though, they stop developing and even lose some skills." Its symptom list includes "Loss of speech." Rett syndrome occurs mostly in girls and is diagnosed by a doctor.
How common is regression in autism? Why you hear different numbers
Estimates of regression in children with autism run from about 20 percent to over 80 percent. Both ends come from real studies. The number depends on how the researchers looked.
| How researchers looked | What they found | Source |
|---|---|---|
| Studies of whole populations | 21.8% | Barger 2013, meta-analysis |
| Studies of clinic patients | 33.6% | Same meta-analysis |
| Parent surveys | 40.8% | Same meta-analysis |
| Watching babies over time | 86.4% (19 of 22) showed declines in social communication | Ozonoff 2010 |
Outside expert, not affiliated with Budding FuturesThis corpus of literature suggests that regressive onset patterns occur much more frequently than previously recognized and may be the rule rather than the exception.
Why the gap? The same paper explains: "While retrospective studies yielded regression estimates of 20-30%, prospective data put them much higher, in some studies well over 80%." Asking parents to remember catches the sudden losses. Watching babies over time also catches the slow ones.
One caution. Those baby studies followed younger siblings of autistic children, so they are not a number for all children.
Our own count: studies on regression, by year
We counted published papers with regression in the title that also deal with autism and language, speech or skills, in the Europe PMC research database. There were about 3 to 6 a year in the early 2010s and 8 to 10 a year since 2020.
Will my child talk again? What the research can and cannot say
Nobody can promise an answer for one child. Here is what studies of groups of children say.
The study that followed 408 children to age 10
Outside expert, not affiliated with Budding FuturesAlthough language regression can be alarming, our findings confirm that its occurrence does not necessarily foreshadow worse developmental outcomes relative to those without regression.
The study had interview data on 408 children with autism. Ninety of them, 22%, had language regression. The honest detail is in the next finding: "those with language regression continued to exhibit expressive but not receptive communication delay compared to those without regression."
In plain words: on understanding language, they did as well as the children who never regressed. On speaking, they stayed behind.
How many children regain lost skills
One large U.S. study gives a number. Reyes and colleagues (2024) studied preschoolers with autism and reported: "26% of children experienced social and language regression, and of those with regression, 76% had regained lost skills upon completion of the study."
Three limits. The information came from parent interviews. "Regained" does not mean caught up with other children. And the same paper warns that "children with regression are at risk for poorer outcomes during their preschool years." An older review by Rogers (2004) was less hopeful about later recovery, and noted that many children who regress had shown "previous, subtle, developmental differences" before the loss.
So here is the fair summary. In one large study, most parents saw lost skills come back. How complete that return is, nobody has settled.
One number we left out: a figure of 43% that at least one high-ranking page prints for children who regain speech. We could not find a study behind it.
Do vaccines cause regressive autism?
No link has been found. Parents often ask because regression tends to show up in the second year, when children also get routine shots.
The largest pooled analysis we found included "Five cohort studies involving 1,256,407 children, and five case-control studies involving 9,920 children." Its conclusion: "Findings of this meta-analysis suggest that vaccinations are not associated with the development of autism or autism spectrum disorder" (Taylor, Swerdfeger and Eslick, University of Sydney, 2014).
That paper looked at autism as a whole, not at regression on its own.
Where ABA fits, and where it does not
Budding Futures does not diagnose autism and does not provide speech therapy
Your first calls are to the pediatrician and to the state, not to us. A diagnosis comes from a doctor or psychologist. Speech therapy comes from a speech-language pathologist. If you need help finding an evaluation, see autism testing for kids in Colorado. If you are not sure which it is, read speech delay vs autism.
What in-home ABA works on alongside a speech-language pathologist
In-home applied behavior analysis (ABA) can work on communication inside daily routines: asking for things, following simple directions, taking turns. At Budding Futures the therapy is play-based and assent-based, and a BCBA writes each child's plan. If your child has Health First Colorado, the state's behavioral therapy benefit does not require an autism diagnosis when therapy is medically necessary.
More on what that looks like: ABA therapy for speech delay and ABA vs speech therapy.
For children under 5, start with early intervention ABA in Colorado, or go to your city: Denver, Colorado Springs, Aurora or Fort Collins.
Our own video: ABA vs Speech vs OT Therapy in Colorado: What Does Your Autistic Child Need?
Questions parents ask about regression
Is regression always autism?
How long does autism regression last?
Why did my child lose words at 18 months?
Is it regression or just a pause?
What is regressive autism?
Can ABA therapy help after speech regression?
Sources
- American Academy of Pediatrics, HealthyChildren.org. 3 Early Signs of Autism in Children, last updated September 26, 2025, and Language Delays in Toddlers.
- Centers for Disease Control and Prevention. Milestones by 2 Years, page dated May 15, 2026.
- American Speech-Language-Hearing Association. Autism and Autism Spectrum Disorder, Practice Portal.
- Barger BD, Campbell JM, McDonough JD. Prevalence and onset of regression within autism spectrum disorders: a meta-analytic review. Journal of Autism and Developmental Disorders, 2013.
- Ozonoff S, Iosif AM, and colleagues. A prospective study of the emergence of early behavioral signs of autism. Journal of the American Academy of Child and Adolescent Psychiatry, 2010.
- Ozonoff S, Iosif AM. Changing conceptualizations of regression: What prospective studies reveal about the onset of autism spectrum disorder. Neuroscience & Biobehavioral Reviews, 2019.
- Pickles A, and colleagues; Pathways in ASD Study Team. Predictors of language regression and its association with subsequent communication development in children with autism. Journal of Child Psychology and Psychiatry, 2022.
- Reyes N, and colleagues. Social and language regression: characteristics of children with autism spectrum disorder in a community-based sample. Journal of Developmental and Physical Disabilities, 2024.
- Rogers SJ. Developmental regression in autism spectrum disorders. Mental Retardation and Developmental Disabilities Research Reviews, 2004.
- Taylor LE, Swerdfeger AL, Eslick GD. Vaccines are not associated with autism: an evidence-based meta-analysis of case-control and cohort studies. Vaccine, 2014.
- NIH Genetic and Rare Diseases Information Center. Landau-Kleffner syndrome. National Library of Medicine, MedlinePlus. Rett Syndrome.
- Early Intervention Colorado, Colorado Department of Early Childhood. Colorado Department of Education, Referral for Special Education Evaluation in Colorado, September 2024. 34 CFR 303.310 and 34 CFR 300.301.
- Budding Futures count of Europe PMC records by publication year, run October 7, 2026.
Not sure what your next step is?
If your child has a diagnosis, or you are waiting on one, we can talk through what in-home ABA would look like and check your benefits. If the first step is your pediatrician or the state, we will tell you that.
- Every plan is written and supervised by a BCBA
- No waitlist, and we verify your benefits free before anything starts
- Health First Colorado (Medicaid)
- Aetna
- Cigna
- UnitedHealthcare
- Anthem BCBS
- TRICARE