Autism can show signs as early as the first year of life, but what counts as a red flag shifts a lot depending on your baby's age. A pattern that would be concerning at nine months is often completely ordinary at three months, which is part of why it can be so hard for parents to know what they are actually looking at. Below is a checklist broken down by age, built around the skills babies are typically building at each stage.
Why Age Matters So Much Here
Autism sits on a spectrum, and signs can appear anywhere from two months to two years or later. Some babies develop typically for a while and then plateau or lose skills they had already gained, sometimes as late as eighteen months. Because of that range, a single snapshot in time tells you less than watching for a pattern across several months. The checklist below is meant to be used that way, as a reference to revisit at each stage rather than a one-time test.
By 3 Months
- Does not watch moving objects or a caregiver's face
- Does not respond to loud noises
- Does not grasp objects or bring hands to their mouth
- Does not smile at people or make eye contact
- Has not started babbling
By 7 Months
- Does not turn toward the source of a loud sound
- Shows no clear signs of affection toward caregivers
- Does not laugh, squeal, or make vowel-like sounds
- Does not reach for objects or engage in games like peekaboo
- Does not attempt to get attention through sounds or movement
- Seems unusually stiff or unusually floppy
By 9 Months
- Is less responsive to hearing their own name
- Does not copy sounds or gestures made by others
- Does not look in the direction someone is pointing
- Cannot sit up without support
- Does not pass toys from one hand to the other
By 12 Months
- Is not crawling
- Has not said a single word
- Does not wave, shake their head, or use other gestures
- Does not point to objects or pictures
- Cannot stand while holding onto support
By 18 Months
- Only repeats words heard on a screen rather than using new words
- Is not walking
- Does not recognize familiar objects like a cup or spoon
- Is not gaining new words
- Does not react when a parent leaves the room or returns
By 24 Months
- Loses a skill they previously had
- Is not combining two words into a phrase
- Does not notice when a parent is hurt or upset
What Sits Underneath These Signs
Before more advanced skills like speech, social interaction, and emotional regulation can develop, four more basic areas of nervous system function need to be working well: sleep and the ability to self-soothe, digestion and motility, respiratory and immune function, and motor development and movement. When one of these foundational areas has been under stress since early infancy, often traced back to a combination of prenatal stress, birth stress, low oxygen at birth, or early exposure to toxins, the more advanced skills built on top of that foundation can be affected too. It is a combination of factors working together rather than any single cause, what our practice calls the Perfect Storm, and no one factor on that list guarantees anything on its own. You can read more about how we look at that pattern on our Perfect Storm page.
This is also why two babies with a very similar birth story can end up on completely different paths. Genetics play a real role too, and researchers increasingly describe autism as sitting at the intersection of inherited tendencies and environmental load, rather than being caused by one or the other alone.
If You Are Noticing These Signs
Parents are usually the first to notice, and studies on parent reporting have found that a caregiver's own instinct about a disability is right far more often than not. Well-child visits typically include a general developmental check around 9, 18, and 24 to 30 months, with a check aimed specifically at autism added at 18 and 24 months, plus anytime a concern comes up outside those windows. Support tends to go further the earlier it starts, since a baby's nervous system is unusually responsive to input in these first few years.
A Checklist Is a Starting Point, Not a Verdict
It bears repeating that missing one sign at one age is common and, on its own, rarely means much. What tends to matter more is a cluster of missed signs at a given age, or skills that were present and then disappeared. A baby who babbles late but points, waves, and makes eye contact is telling a very different story than a baby who is missing several signs across more than one category at the same age. Use the checklist to notice patterns worth a closer look, not to score your baby against a list.
How Our Doctors Look at Early Development
Rather than working from behavior checklists alone, our doctors combine a gentle physical exam with INSiGHT neurological scanning to get an objective read on how your baby's nervous system is actually functioning: motor coordination, muscle tone, and overall neurological patterns. Using Koren Specific Technique and Talsky Tonal Chiropractic, care involves light, nervous system focused contacts aimed at easing tension carried from pregnancy, birth, and whatever stress has built up since, supporting the neuromotor coordination that these early milestones depend on.
What Parents Often Notice
Families commonly describe steadier eye contact, more back and forth engagement, smoother motor coordination, and a baby who seems calmer and more settled overall. Because these foundational areas overlap, sleep and digestion sometimes shift alongside social and motor gains, even when a parent came in focused on just one concern.
Where to Go From Here
If your baby is missing several of these signs at the right age for them, take that seriously rather than waiting to see. Read more about our approach to autism and neurodevelopmental care, and grab our free guide for a deeper look at what drives early developmental patterns. Reach our Royal Oak office by phone at (248) 616-0900, or go ahead and book online.
