Early Signs of Autism in Toddlers: A Guide by Age for Parents

The early signs of autism in toddlers usually show up before age 2 and mostly involve social communication and play: for example, not responding to their name by about 9 to 12 months, not pointing to show you something by about 14 to 18 months, or repeating the same actions with toys over and over^{1, 2, 4}. One sign alone does not mean a child is autistic, and some autistic children don't show these signs at all^{2, 4}. If something worries you, talk to your pediatrician and ask for an evaluation: you don't need a diagnosis to get early help^{1, 8}.

What is autism?

Autism spectrum disorder (ASD) is a difference in development that affects how a person communicates, relates to others, learns and behaves³. It is called a "spectrum" because autistic people have a wide range of characteristics, needs, strengths and challenges³. Many have strengths such as remembering details for a long time, learning well by seeing or hearing, or doing very well in music, art, math or science³.

Autism can be diagnosed at any age, but the first signs usually appear in the first two years of life³. A specialist can usually make a reliable diagnosis by age 2, and sometimes as early as 18 months^{1, 3}. Knowing early means support can start sooner³.

Early signs of autism in toddlers, by age

Every child develops at their own pace. These ages come from the American Academy of Pediatrics (AAP) and the Centers for Disease Control and Prevention (CDC). Use them as a guide for talking with your pediatrician, not as a test^{1, 2}.

• By about 9 months: doesn't respond when you call their name, or shows few facial expressions such as happy, sad or surprised².
• By about 12 months: uses few or no gestures, like waving bye-bye, and doesn't play simple back-and-forth games like pat-a-cake^{1, 2}.
• By about 14 to 15 months: doesn't point at things to show interest, or bring you objects to show you^{1, 2}.
• By about 18 months: doesn't point to share something interesting, and doesn't pretend play, like feeding a doll^{1, 2}.
• By about 24 months: doesn't seem to notice when someone else is hurt or upset².
• By about 3 years: doesn't notice other children or join them in play².

Social communication

In toddlers, researchers have found that the first differences are often in social attention: looking at faces less, smiling back less, imitating less, or sharing attention with you less, such as looking where you point⁴. Many parents say one of their first concerns was that their child didn't turn when they heard their name⁴. Some children also have delayed language^{1, 2}.

Play, interests and repetitive behaviors

• Lines up toys and gets upset when someone changes the order².
• Plays with toys the same way every time, or focuses on one part, like the wheels on a toy car².
• Gets very upset by small changes in routine^{1, 2}.
• Repeats words or phrases over and over; this is called echolalia^{1, 2}.
• Flaps hands, rocks or spins in circles^{1, 2}.
• Reacts in unusual ways to sounds, smells, tastes, textures or lights^{1, 2}.

When a child loses skills

Some children develop as expected and then stop using words or social skills they already had. The AAP estimates this happens to about one in four autistic children, most often between 18 and 24 months^{1, 4}. Losing skills at any age is a reason to talk with your pediatrician soon⁹.

What research says about early signs of autism

A group of experts reviewed the research on early identification of autism⁴. They concluded that between 12 and 24 months, the most useful signs are less social attention and communication and more repetitive behavior with objects⁴. Reliable signs have not yet been found before 12 months, and some studies saw no differences at 6 months⁴. Autism also shows up in very different ways: some children show differences very early, others have a speech delay in their second year, and others lose skills after a period of typical development⁴.

The M-CHAT-R/F: the 18- and 24-month screening

The AAP recommends that every child have an autism-specific screening at the 18- and 24-month checkups, in addition to general developmental screening at 9, 18 and 30 months^{1, 8}. One of the most widely used tools is the M-CHAT-R/F, a parent questionnaire for children 16 to 30 months old¹. If the result shows some risk, the professional asks follow-up questions to clarify the answers¹.

In the study that validated the M-CHAT-R/F, nearly half (47.5%) of the children who screened positive after follow-up were diagnosed with autism, and almost all (94.6%) had some developmental delay or concern⁵. In other words, a positive screen is not a diagnosis, but it is a clear sign that an evaluation is worthwhile^{1, 5}. A systematic review of 50 studies found that the M-CHAT identifies most autistic children, and that the follow-up questions greatly reduce false positives⁶. Still, accuracy varied a lot between studies, some autistic children don't screen positive, and few studies repeated the screening at both 18 and 24 months⁶. So if you are still worried after a normal screen, tell your pediatrician.

Where experts disagree

In 2016, the U.S. Preventive Services Task Force (USPSTF) concluded that there is not enough evidence to know whether the benefits of screening all young children, when no one has concerns, outweigh the harms⁷. That is not a recommendation against screening. The Task Force also says that when parents or clinicians raise concerns, those concerns should be listened to carefully and checked with validated tools such as the M-CHAT⁷. The AAP continues to recommend screening at 18 and 24 months¹.

What you can do at home

1. Track milestones. The CDC has checklists by age and a free app, Milestone Tracker (in Spanish, Sigamos el Desarrollo)^{8, 9}. Bring them to every checkup.
2. Write down what you see. Note specific examples and when they started: "doesn't turn when I call him," "lines up his cars." That gives your pediatrician clear information.
3. Play face to face. Get down to your child's level, follow what interests them and wait for their response. Name what they look at or point to.
4. Ask about autism screening at the 18- and 24-month checkups, even if no one has mentioned it^{1, 8}.
5. Trust your instincts. Many parents notice something before 18 to 24 months⁴. If you are worried, don't wait to see if it "goes away"⁸.

When to seek help

Talk with your pediatrician soon if:

• Your child doesn't respond to their name by about 12 months¹.
• Doesn't point to show you things by about 14 to 18 months^{1, 2}.
• Doesn't pretend play by about 18 months¹.
• Loses words or social skills they had, at any age⁹.
• Screened positive on the M-CHAT-R/F or another screening tool¹.
• Isn't reaching one or more milestones for their age, or something just doesn't feel right to you^{8, 9}.

Steps you can take

1. Talk with your pediatrician and share your notes. Ask for a screening and, if needed, a referral to a specialist, such as a developmental pediatrician, child neurologist or child psychologist⁸.
2. If your child is under 3, call your early intervention program. In Florida it is called Early Steps, and it serves children from birth to 36 months who show signs of developmental delay or whose parents or doctors have concerns¹⁰.
3. If your child is 3 or older, call a local public elementary school, even if your child doesn't go there, and ask for a preschool special education evaluation⁸.

You don't need to wait for a diagnosis or a doctor's referral to request this evaluation, and it is free⁸. The AAP also says a definitive diagnosis is not needed to start services for a developmental delay, and that a child who screens positive should be referred for a diagnostic evaluation and intervention services at the same time¹.

For more in plain language, see the CDC's page Concerned About Your Child's Development?.

How we help at Healthy Solutions

At Healthy Solutions for Children and Families in Doral, our ABA therapy starts with a detailed assessment of each child's skills and an individual plan, with goals the family helps shape, such as communication, play and daily living. Sessions can take place at home, at school or in the community, and progress is reviewed with the family. To learn more about how it works, read what ABA therapy is; to see the evaluations we offer, visit insurance and evaluations, or write to us with your questions.

Sources

1. Hyman SL, Levy SE, Myers SM; AAP Council on Children With Disabilities, Section on Developmental and Behavioral Pediatrics (2020). Identification, Evaluation, and Management of Children With Autism Spectrum Disorder. Pediatrics (American Academy of Pediatrics). DOI: 10.1542/peds.2019-3447.
2. Centers for Disease Control and Prevention (2024). Signs and Symptoms of Autism Spectrum Disorder (Signos y síntomas de los trastornos del espectro autista). CDC.
3. National Institute of Mental Health (2025). Autism Spectrum Disorder (Trastornos del espectro autista), NIH Publication No. 25-MH-8084. National Institute of Mental Health (NIMH).
4. Zwaigenbaum L, Bauman ML, Stone WL, Yirmiya N, Estes A, Hansen RL, McPartland JC, Natowicz MR, Choueiri R, Fein D, Kasari C, Pierce K, Buie T, Carter A, Davis PA, Granpeesheh D, Mailloux Z, Newschaffer C, Robins D, Smith Roley S, Wagner S, Wetherby A (2015). Early Identification of Autism Spectrum Disorder: Recommendations for Practice and Research. Pediatrics. DOI: 10.1542/peds.2014-3667c.
5. Robins DL, Casagrande K, Barton M, Chen CM, Dumont-Mathieu T, Fein D (2014). Validation of the Modified Checklist for Autism in Toddlers, Revised With Follow-up (M-CHAT-R/F). Pediatrics. DOI: 10.1542/peds.2013-1813.
6. Wieckowski AT, Williams LN, Rando J, Lyall K, Robins DL (2023). Sensitivity and Specificity of the Modified Checklist for Autism in Toddlers (Original and Revised): A Systematic Review and Meta-analysis. JAMA Pediatrics. DOI: 10.1001/jamapediatrics.2022.5975.
7. US Preventive Services Task Force (2016). Autism Spectrum Disorder in Young Children: Screening (Final Recommendation Statement). US Preventive Services Task Force (USPSTF).
8. Centers for Disease Control and Prevention, Learn the Signs. Act Early. (2026). Concerned About Your Child's Development? (¿Le preocupa el desarrollo de su hijo?). CDC.
9. Centers for Disease Control and Prevention, Aprenda los signos. Reaccione pronto. (2026). Indicadores del desarrollo de los CDC (CDC's Developmental Milestones). CDC.
10. Florida Department of Health (2026). Early Steps. Florida Department of Health (Clay County).