Early signs of autism

Early signs of autism in babies and toddlers include not meeting developmental milestones for language and social skills, not interacting with others, and having repetitive or rigid behaviors. For kids ages 2 and up, red flags include language delays, extreme sensitivity, and behavior problems such as aggression or impulsivity. The earlier a child with autism begins treatment, the better the outcome – so if you have any concerns about how your child is developing, talk to their doctor right away.

toddler manipulating toy while sitting at table
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It can be hard to tell whether a child has autism because children who don't have the condition can show some of the same behavior. Most children with autism spectrum disorder (ASD) don't get a diagnosis until they're 4 or older.

But it's possible to get a reliable autism diagnosis as early as age 2. And many parents notice early signs of autism – even before their baby's first birthday – and realize something is different by the time their child is 18 months old.

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Your child's doctor should screen for autism at well-child checkups at 18 and 24 months. But if you notice any of these signs (even if it's only a few) or have any concerns about your child's development, bring it up with their doctor as soon as possible. Don't wait to see if your child will grow out of it.

Signs of autism in babies

Before your baby is 1 year old, picking up on signs of autism means paying attention to whether they're meeting developmental milestones.

In one study of the early signs of autism (known as the Avon study), researchers found that, among children later diagnosed with ASD, concerns about vision and hearing were often reported in the first year. From age 6 months on, differences in social development, communication, and fine motor skills were evident. 

Also, it's a red flag if your baby:

  • Doesn't show interest in faces.
  • Doesn't make eye contact, doesn't smile, and may seem to look right through you.
  • Doesn't always react to sounds. Doesn't respond to their name, for example, or doesn't turn around to see where a sound is coming from. In other situations, their hearing may seem fine.
  • Doesn't like being cuddled or touched.
  • Doesn't show interest in typical baby games, like peekaboo.
  • Doesn't babble or show other early signs of talking.
  • Doesn't use gestures, like reaching for you when they want to be held.

Signs of autism in toddlers

Repetitive behaviors and differences in play, imitation, and feeding habits were the most often reported signs of autism in the second year, according to the Avon study.

Also look for these signs:

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  • Doesn't use gestures. Doesn't shake their head yes or no. Doesn't wave goodbye or point to things they want.
  • Doesn't point out objects to show interest in the world around them. By 14 to 16 months, most toddlers point to get your attention and share something they're interested in, such as a puppy or new toy.
  • Doesn't use single words by 16 months or two-word phrases by 24 months.
  • May limit speech to repeating what they just heard.
  • Loses verbal or social skills, often between the ages of 15 and 24 months. Used to babble or speak a few words, or show interest in people, but now doesn't.
  • Withdraws. Seems to tune people out and be in their own world.
  • Walks on their toes or doesn't walk at all.

Signs of autism in children 2 and up

In the Avon study, differences in temperament emerged at 2 years old. By 30 months, children with autism had differences in their bowel habits. (Children with autism have more gastrointestinal symptoms – such as constipation, diarrhea, bloating, and abdominal pain – than other children.)

Other signs you might notice:

  • Has a language delay. May struggle to express their needs. Some children with autism don't speak, while others develop language but have trouble participating in a conversation.
  • Has unusual speaking patterns. Might speak haltingly, in a high-pitched voice or a flat tone. Might use single words instead of sentences or repeat a word or phrase. Might repeat a question rather than answer it.
  • Doesn't enjoy playing with others, even parents.
  • Doesn't show empathy for others.
  • Has difficulty making and keeping friends.
  • May have a good rote memory, especially for songs, numbers, letters, TV jingles, or a specific topic.
  • Doesn't seem to understand what people are saying to them. May not respond to their name or may be unable to follow directions. May laugh, cry, or scream inappropriately.
  • Narrowly focuses on a single object, one thing about an object (like a wheel on a toy car), or one topic at a time.
  • Engages in limited imitation. Rarely mimics what you do and doesn't engage in pretend play.
  • Seems content to play alone. Appears to have little interest in other children and usually doesn't share or take turns.
  • Displays rigid behavior (beyond what seems usual for a 2-year-old). May be very attached to routines and have difficulty with transitions. For example: A change in the usual route home from daycare can throw them into despair or result in a tantrum.
  • Is very particular about what they will and won't eat. May want to follow strict rituals when having snacks and meals.
  • Plays with objects or toys in unusual ways. For example, spends a lot of time lining things up or putting them in a certain order. May enjoy repetitively opening and closing a door. Or may become preoccupied with repeatedly pushing a button on a toy or spinning the wheels of a toy car.
  • Engages in self-injury, such as biting or hitting themselves.
  • Exhibits repetitive actions, such as flapping their arms or hands.
  • Is overly sensitive to various kinds of stimulation. May resist touch, get agitated by noise, and be extremely sensitive to smells. May want to wear only clothes without tags or made of a certain material.
  • May overreact to some types of pain and underreact to others. For example, they may cover their ears to block loud noises but not notice when they skin their knee.
  • May be fearful when it's unnecessary or fearless when there's reason to be afraid. For example, they may be afraid of a harmless object, like a balloon, but not frightened of heights.
  • Has sleep disturbances. Many children with autism have trouble falling asleep and wake up frequently in the night, or are very early risers.
  • Exhibits behavior problems. May be resistant, uncooperative, hyperactive, impulsive, or aggressive.
  • May have unusual gaze, looking at objects from unusual angles.

Learn more:

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Karen Miles
Karen Miles is a writer and an expert on pregnancy and parenting who has contributed to BabyCenter for more than 20 years. She's passionate about bringing up-to-date, useful information to parents so they can make good decisions for their families. Her favorite gig of all is being "Mama Karen" to four grown children and "Nana" to nine grandkids.