Reviewed by a licensed speech-language pathologist
Quick answer: Whether to retake the M-CHAT depends on your child’s age, the first score, and how much time has passed. Screening twice, once around 18 months and again near 24 months, is normal and recommended. If a first result was medium risk, the usual next step is the follow-up interview, not simply redoing the questionnaire.
Many parents fill out the M-CHAT once, look at the score, and immediately wonder if they should do it again. Maybe the day was chaotic, maybe the toddler was tired, or maybe a borderline result left more questions than answers. The good news is that repeat screening is built into how the tool is meant to be used. The trick is knowing when to retake, when to move to a follow-up interview, and when to talk with a professional instead.
What is the M-CHAT and how is it scored?
The Modified Checklist for Autism in Toddlers, Revised, is a short questionnaire parents answer about their child’s early social and communication behaviors. Based on the answers, a child falls into low, medium, or high risk for autism spectrum disorder. The official M-CHAT-R materials explain that a low-risk score usually needs no further action, a medium-risk score is meant to trigger a structured follow-up interview, and a high-risk score points toward a full evaluation without delay.
It helps to remember what the tool is and is not. It is a screener, not a diagnosis. As the Centers for Disease Control and Prevention describes, screening flags whether a closer look is worthwhile; it does not settle the question by itself.
Should I retake the M-CHAT after a first result?
This is where the answer splits by situation. If your child scored in the medium-risk range and you only completed the questionnaire, the correct next step is usually not to redo the same questions. The tool includes a follow-up interview designed to clarify borderline items, and completing that interview often moves a child from medium risk to low risk once the details are understood. Simply retaking the questionnaire skips the step that was built for exactly this moment.
If the first screen was low risk but you have real concerns about how your child plays, points, responds to their name, or shares attention, redoing the checklist can be reasonable, especially if weeks or months have passed. Development at this age moves fast, and a picture from three months ago may no longer match the child in front of you.
How often is the M-CHAT supposed to be repeated?
Routine practice is to screen at both the 18-month and 24-month well visits. The American Academy of Pediatrics supports autism-specific screening at these ages precisely because a child can look one way at 18 months and different at 24 months. So retaking the M-CHAT is not unusual or a sign that something went wrong. It is part of the standard schedule.
Beyond those two points, an extra screen can make sense if new concerns appear, if a child regresses in skills they had, or if a clinician wants a fresh reading before deciding on next steps.
Can the result really change between screenings?
Yes, and this surprises a lot of families. A toddler who was quiet and cautious at 18 months may be pointing, babbling, and imitating by 24 months, shifting the score downward. Another child may show emerging signs at 24 months that were not obvious earlier. Neither outcome is a mistake. The CDC’s milestone materials show how much typical development stretches and changes across these months, which is why a single snapshot carries only so much weight.
Because scores can move, one screen alone should not lock in a conclusion in either direction. Two data points, plus your own observations over time, give a steadier read than any single result.
What should I do while I wait for answers?
If you are between a first screen and a follow-up, or waiting on an evaluation, there are useful things to do in the meantime. Keep a short log of what you notice week to week: gestures, eye contact, new words, and how your child responds to their name. That record makes the follow-up interview far more accurate than trying to recall everything on the spot.
You can also build gentle communication practice into everyday play. Narrate what you are doing, pause to let your child take a turn, and reward any attempt to connect. Some families add short daily speaking practice using voice-first tools such as the Little Words speech companion, which turns language practice into low-pressure play a parent can lead at home. Home practice like this is a supplement to professional screening and any therapy that follows, not a substitute for either, and it should stay light and encouraging rather than becoming a test.
When should I stop screening and talk to a professional?
A high-risk score is not a moment to keep rescreening at home. It is a signal to reach out to your pediatrician and request a developmental evaluation. The same is true if the follow-up interview keeps a child in the medium-risk range, or if your gut concern stays strong regardless of the number. The Autistic Self Advocacy Network reminds families that a screening result is information, not a verdict, and that early support can help a child regardless of how the assessment turns out.
Key takeaways
- Screening twice, near 18 and 24 months, is standard, so retaking the M-CHAT is often expected rather than unusual.
- After a medium-risk questionnaire, the follow-up interview is the right next step, not simply redoing the checklist.
- Results can shift between screenings because early development changes quickly, so two readings beat one.
- The M-CHAT is a screener, not a diagnosis, and a high-risk score should lead to a professional evaluation.
- Keeping notes and adding gentle daily communication practice can help while you wait for next steps.
Frequently asked questions
How often should the M-CHAT be given?
Standard practice is at both the 18-month and 24-month checkups, since some signs become clearer over those six months. A repeat screen at another point can make sense if concerns come up between visits.
Can the M-CHAT result change between screenings?
Yes. Development moves quickly at this age, so a child can screen low-risk at 18 months and medium or high risk at 24 months, or the other way around. That is one reason two screenings are recommended.
Should I retake the M-CHAT if the first result worries me?
If you completed only the questionnaire, the next step is usually the follow-up interview rather than simply redoing it. A medium-risk score is designed to be clarified by that interview, not repeated on its own.
Is the M-CHAT a diagnosis?
No. It is a screening tool that flags whether a fuller evaluation is worth pursuing. Only a qualified professional can diagnose autism through a broader assessment.
What age is the M-CHAT for?
The M-CHAT-R is designed for children roughly 16 to 30 months old. Outside that window, other tools and a direct conversation with a clinician are more appropriate.
Sources
- Modified Checklist for Autism in Toddlers, Revised (M-CHAT-R): Official Site (mchatscreen.com)
- Centers for Disease Control and Prevention: Screening and Diagnosis of Autism Spectrum Disorder (cdc.gov)
- American Academy of Pediatrics (HealthyChildren.org): Autism Spectrum Disorder (healthychildren.org)
- Centers for Disease Control and Prevention: Developmental Milestones (Learn the Signs. Act Early.) (cdc.gov)
- Autistic Self Advocacy Network (autisticadvocacy.org)
