Signs of autism

One of the most important things you can do as a parent or caregiver is to learn the early signs of autism and become familiar with the developmental milestones that your child should be reaching.

The list below gives some examples of common types of behaviors you might see in children diagnosed with autism spectrum disorder (ASD). Not all autistic children will have all these behaviors, but most will have several of the behaviors listed below. That’s why professional evaluation is crucial. Additionally, some children without ASD might display some of these behaviors. But for those with ASD, these behaviors can be disruptive or challenging to daily life. 

Signs of autism in babies infographic

Signs of autism in babies

By 6 months

  • Few or no big smiles or other warm, joyful and engaging expressions
  • Limited or no eye contact

By 9 months

  • Little or no back-and-forth sharing of sounds, smiles or other facial expressions


Signs of autism in toddlers infographic

Signs of autism in toddlers

By 12 months

  • Little or no babbling
  • Little or no back-and-forth gestures such as pointing, showing, reaching or waving
  • Little or no response to name

By 16 months

  • Very few or no words

By 24 months

  • Very few or no meaningful, two-word phrases (not including imitating or repeating)


Signs of autism infographic

Signs of autism at any age

  • Loss of previously acquired speech, babbling or social skills
  • Avoidance of eye contact
  • Persistent preference for solitude
  • Difficulty understanding other people’s feelings
  • Delayed language development
  • Persistent repetition of words or phrases (echolalia)
  • Resistance to minor changes in routine or surroundings
  • Restricted interests
  • Repetitive behaviors (flapping, rocking, spinning, etc.)
  • Unusual and intense reactions to sounds, smells, tastes, textures, lights and/or colors


At what age is autism diagnosed?

Autism can be reliably diagnosed by the age of 2

Age of autism diagnosis and early signs of autism can vary widely from child to child. Some children show early signs of autism within the first 12 months of life. In others, autism signs may not show up until 24 months of age or later. Importantly, some children with ASD gain new skills and meet developmental milestones until around 18 to 24 months of age, and then they stop gaining new skills or lose the skills they once had.

The American Academy of Pediatrics (AAP), the leading pediatric health organization in the United States, recommends that all children be screened for autism at ages 18 months and 24 months, in addition to undergoing developmental and behavioral screenings during their regular well-child visits at 9 months, 18 months and 30 months. Research shows that by age 2, an ASD diagnosis by an experienced professional can be considered reliable.

If you have concerns about your child’s development:

  1. Learn the signs. The Centers for Disease Control and Prevention (CDC) Act Early program provides parents, childcare professionals and pediatric clinicians with free resources, in English and Spanish, for monitoring a child’s development. The program offers parent-friendly, research-based milestone checklists for children as young as 2 months of age. The Milestone Tracker App can help parents track their child’s development and share the information with their pediatricians.
  2. Take the M-CHAT-R screening questionnaire. The M-CHAT-R (Modified Checklist for Autism in Toddlers, Revised) can help you determine if a professional should evaluate your child. This simple online autism screening questionnaire, available on our website, takes only a couple minutes to complete. If the answers suggest your child has a high probability for autism, please consult with your child’s doctor. Watch the video below to see how the M-CHAT-R™ helped Eileen get an autism diagnosis for her son, Charlie.
  3. Schedule an appointment with your child’s pediatrician. If you have any concerns about your child’s development, don’t wait. Speak to your doctor now about screening your child for autism. You can use the Autism Speaks Resource Guide to find providers near you. While every child develops differently, early intervention can improve outcomes, often dramatically. For example, studies show that early intensive behavioral intervention improves learning, communication and social skills in young children with ASD.

Related resources

Contact the Autism Response Team

Autism Speaks' Autism Response Team can help you with information, resources and opportunities.

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