Early signs of autism in infants, toddlers, and preschoolers

According to the Centers for Disease Control and Prevention (CDC), about 1 in 54 school-aged children in the United States has been identified with autism spectrum disorder (ASD), a condition characterized by difficulties with social interactions and behavioral challenges. Boys are four times more likely to be diagnosed with autism than girls, as girls may be more likely to have symptoms, such as social impairment, that are harder to detect than behavioral issues.

The importance of early diagnosis

The American Academy of Pediatrics (AAP) joins with the CDC in recommending screening at a young age to ensure early intervention and better developmental outcomes. In the U.S., most autism costs are for an adult rather than child services ($175–196 billion for adults versus $61–66 billion for children). However, with early diagnosis and treatment, the cost of care over a lifetime can be reduced by two-thirds. 

Checklists of autism signs

Through its “Learn the Signs. Act Early” campaign, the CDC aims to raise awareness of the early signs of developmental delay, including autism. Through milestone checklists, the CDC provides information on what most babies do at different ages and which signs parents should discuss with their child’s doctor. Milestones are included for children 2 months to 5 years of age, reflecting a belief among researchers that even infants may show early autism signs.

Early signs of autism or other developmental delays include the following: 

  • 2 months: Doesn’t respond to loud sounds, watch things as they move, smile at people, or bring hands to mouth. Can’t hold head up when pushing up while on tummy.
  • 4 months: Doesn’t try to get things in reach, respond to sounds around him, make vowel sounds (“ah,” “eh,” “oh”), roll over in either direction or laugh or squeal. Pays no attention to caregivers. Has difficulty getting things to his mouth. Seems stiff or floppy.
  • 6 months: Doesn’t watch things as they move, smile at people, “coo” or make sounds, bring objects to her mouth, or push down with her legs when her feet are placed on a hard surface. Can’t hold head steady. Has trouble moving one or both eyes.
  • 9 months: Doesn’t stand with support, sit with help, babble (“mama,” “baba,” “dada”), play games with back-and-forth interaction, transfer toys from one hand to the other, respond to own name, look where you point, or seem to recognize familiar people. 
  • 12 months: Doesn’t crawl, stand with support, search for things he sees you hide, say simple words like “mama” or “dada,” gesture (waving hands, shaking head), or point to objects of interest. Loses skills he once had. 
  • 18 months: Doesn’t point to objects of interest, copy others, gain new words, use at least six words, or notice or mind when a caregiver leaves or returns. Doesn’t know what to do with familiar objects (like a spoon or a brush). Loses skills. 
  • 2 years: Doesn’t use two-word phrases (“drink milk”), copy actions or words, follow simple instructions, or walk steadily. Loses skills. 
  • 3 years: Falls a lot. Has trouble climbing stairs. Can’t work simple toys. Doesn’t speak in sentences. Drools or has unclear speech. Doesn’t play pretend or make-believe. Doesn’t want to play with toys or other children. Doesn’t make eye contact. Continues to lose skills.

Next steps

You can review all major milestones through the first year here for more information on typical infant development.

An additional tool for parents of infants and toddlers who are concerned and want to review their child’s development is a free series of age-specific online books, including Baby’s Busy Day – Being One is So Much Fun!, Where is Bear? – A Terrific Tale for 2-Year-Olds, and Amazing Me: It’s Busy Being 3! Each book features an appealing character engaging in activities typical of a child at that age and demonstrating appropriate skills. Prompts alongside the text ask parents to reflect on how their child is doing with these skills, and a milestone checklist appears at the end of the book and on the accompanying website

Milestone markers are guidelines, not hard-and-fast rules; all children develop at their own pace. But early intervention is crucial in helping children with autism get the help they need. Your child’s healthcare provider will assess her growth at each well-visit to ensure she’s developing well physically, mentally, and behaviorally. But if you have concerns about your child’s development during the course of any year, immediately make an appointment with her healthcare provider. 

Last updated December 6, 2021

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