Sarah was a first-time mom, and she was over the moon when her son, Michael, was born. He was a healthy baby, and Sarah loved spending time with him. But as Michael got older, Sarah started to worry. He wasn’t meeting the same developmental milestones as other babies his age. He didn’t make constant eye contact as much as other babies, and he didn’t seem to be interested in playing with other children.

Sarah started to research autism spectrum disorder (ASD) online, and she began to think that Michael might have ASD. She was scared and didn’t know what to do. She talked to her pediatrician, who referred her to a specialist for further evaluation.

The specialist evaluated Michael and diagnosed him with development delay. Although still concerned about Michael’s development delay, the diagnosis sparked her curiosity about the differences between autism and developmental delay.

Sarah’s story is a reminder that developmental delays can be scary for parents and can be misunderstood as signs of autism. While developmental delay and autism overlap in some areas, both are distinct conditions. This blog explains the key differences between developmental delay vs autism spectrum disorder (ASD), and is a must-read for all first-time parents.

What are development milestones?

As per the Centers for Disease Control and Prevention (CDC), development milestones are the skills and abilities that most children develop at a certain age. They include simple tasks like making lots of sounds such as “mamamama”, taking a first step, smiling for the first time, banging two things together, waving “bye-bye” and so on.

Children progress through development milestones in all areas of their development, including play, learning, language, behavior, and motor skills. The CDC’s developmental milestones list specific levels of achievement for each age, starting with 1 month and moving through adolescence, categorized into 4 domains:

  1. Social / Emotional Milestones
  2. Language / Communication Milestones
  3. Cognitive Milestones (learning, thinking, problem-solving)
  4. Movement / Physical Development Milestones

Here is an example of a developmental milestone in each category for a 9-month-old baby:

Video credit: CDC, Important Milestones: Your Baby By Nine Months

Social / Emotional Milestone

Shows stranger anxiety i.e the baby is shy, clingy, or fearful around strangers

This milestone shows that the baby is developing their social-emotional skills and is starting to understand the difference between familiar and unfamiliar people.

Video credit: CDC, Important Milestones: Your Baby By Nine Months

Language / Communication Milestone

Waves “bye-bye”

This milestone shows that the baby is developing their language skills and starting to communicate.

Video credit: CDC, Important Milestones: Your Baby By Nine Months

Cognitive Milestone

Bangs two things together

This milestone shows that the baby is developing their fine motor skills and hand-eye coordination.

Video credit: CDC, Important Milestones: Your Baby By Nine Months

Physical Milestone

Gets to a sitting position by herself

This milestone shows that the baby is developing their gross motor skills and mobility.

Why are development milestones important?

Children develop at their own pace, but most reach developmental milestones at similar ages. These milestones are important indicators of a child’s healthy growth and development.

  • Meeting developmental milestones on time is a sign that a child is progressing normally. This is also called neurotypical development.
  • Early achievement of developmental milestones may suggest that a child is ahead of their peers in terms of development.
  • But not reaching milestones on time, or reaching them much later than other children, is a developmental delay – a warning sign or red flag.

According to NIH, developmental delays occur in 10-15% of pre-school children [1]. Children who experience developmental delays are eligible for early intervention services, which are programs designed to help them catch up and reach their full potential.

Speech delay is an example of developmental delay that can affect a child’s ability to communicate effectively.
A speech delay is a condition in which a child does not develop speech skills at the same pace as their peers.
It means that the child is learning to form speech sounds or develop language skills at a slower rate than average.

Developmental delays can be in one specific area (ex. Speech Delay). When your child has this type of developmental delay, it doesn’t mean they are autistic. They might just be what’s known as a “late talker.” Minor development delays, especially when present in one area, are no cause for concern and are usually temporary.

But, if your child has significant ongoing delays or delays in more than two areas, it could indicate a learning disability. Scientifically, a delay in more than two areas is known as Global Developmental Delay (GDD).

How is Autism spectrum disorder different from developmental delays?

Developmental delay and autism spectrum disorder are two different conditions, but they can sometimes present with similar symptoms. A child diagnosed with a disorder on the autism spectrum usually experiences developmental delays. But while developmental delay is usually a temporary issue, Autism Spectrum Disorder (ASD) is a developmental disability caused by differences in the brain [2]. Autism or autism spectrum disorder (ASD) is a lifelong condition with core behavioral symptoms appearing during infancy or early childhood [3] .

Developmental Delay vs Autism Spectrum Disorder - The Major Differences

To help you understand the differences between developmental delay vs autism spectrum disorder (or global developmental delay vs autism spectrum disorder), we have compiled the following table:

Infographic representing the key differences in signs & symptoms of developmental delay vs autism spectrum disorder (ASD)

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Developmental Delay vs Autism Spectrum Disorder - The Key Differences and Similarities

This infographic compares and contrasts developmental milestones and autism spectrum disorder, highlighting the key differences between the two conditions. It is important for first-time parents to understand the differences between the two so they can provide the best possible support for their child.

Developmental Delay Overlap Autism
  • Approximately 17% of children are diagnosed with a developmental delay
  • Around 62.3% of children with global developmental delay were diagnosed with ASD[6]
  • Genetics may be involved
  • Environmental aspects may be involved
  • Early intervention is very important
  • Approximately 2.8% of children are diagnosed with Autism
  • Typically does not occur with other conditions
  • Possible challenges with social communication
  • Possible difficulties in expression and speech
  • Early intervention is very important
  • Often occurs with co-occurring medical conditions
  • May go unrecognized for a number of years
  • Could be masked in high functioning autistic individuals, but a high chance of getting diagnosed at a later point in time
  • May involve more physical attributes and fine motor skills such as walking, running, jumping and coordination
  • Possible difficulty in understanding emotions, expressions and body language

Are Developmental Delays a Sure Way of Detecting Autism?

They are not. In some cases, autistic children may have developmental delays that are not immediately apparent. It has been observed that in many cases, missed milestones can be masked, more subtle or even invisible. This is because autistic children are neurodivergent. This means they aren’t simply delayed; rather they learn and behave differently from their typical peers.
Although every child is unique and displays different symptoms, watch out for these common signs that may indicate your child is autistic.

If you are concerned about your child’s development, it is important to talk to your doctor. Diagnosing autism can be difficult and complex, as it may not be apparent from a single test. That is why we have created a comprehensive guide on Diagnosing Autism – A List of Essential Tests and Key Indicators You Can’t Afford to Ignore. The guide gives a comprehensive list and understanding of all tests for autism including developmental screening tests for autism, diagnostic tests for autism, medical tests for autism and other supplemental tests for autism.

Be it Developmental Delay or Autism, Early Intervention is Important

When a child is diagnosed with autism or other developmental conditions, the best thing to do to aid with their development is to start early intervention as soon as possible. Below is a link of state-wise programs for State Early Intervention Information:

This website provides information about early intervention programs in each state, including eligibility requirements, how to access services, and contact information.

Early intervention specialists can screen for and diagnose autism and other developmental conditions in children from a very young age. The benefits of early intervention in autism (ASD) are life changing. According to a study by National Institute of Child Health and Human Development (NICHD), early intervention for certain children with autism enables remarkable advancement to the extent that the kids no longer fall within the autism spectrum as they grow older.

So, the sooner your child is diagnosed and begins early intervention treatment, the better their chances are of developing important life skills at a young age.


Although some signs and symptoms of developmental delays vs autism spectrum disorder in toddlers may look the same, they are two different conditions. While children with autism usually experience developmental delays in one or more areas, not every child who experiences a delay in their development has autism. In some cases of autistic children, the developmental delays could be masked, subtle or even invisible.

Hence, it is important for parents to understand the differences and know when delays in their children’s development are normal and when they could be a sign of autism or other developmental disorders.

If you are concerned that your child may have developmental delay or autism spectrum disorder, it is important to talk to your pediatrician. They can assess your child’s development and refer you to a specialist for further evaluation if necessary.

Did You Know? Folate Receptor Autoantibodies (FRAAs) may impede proper folate transport.

Folate (vitamin B9) is very important for your child’s brain development!

During pregnancy, it helps prevent neural tube defects and plays a big role in forming a normal and healthy baby’s brain and spinal cord. Folate also helps cells divide and assists in both DNA and RNA synthesis.

Emerging research suggests that the presence of FRAAs negatively impacts folate transport into the brain.

  • Recent studies reveal that a large subgroup of children with autism spectrum disorder (ASD) have FRAAs.
  • This suggests that a possible disruption in folate transport across the blood-cerebrospinal fluid (CSF) barrier may potentially influence ASD-linked brain development.
  • Screening for the FRAAs in your child should be part of your early intervention strategies.

Is there a test for identifying Folate Receptor Autoantibodies (FRAAs)?

Yes, there is a test – The Folate Receptor Antibody Test (FRAT®) has emerged as a diagnostic tool for detecting the presence of FRAAs.

It is important to screen at an early age or as soon as possible as there may be corrective measures available. Please consult your physician for further information.

To order a test kit, click on the button below.

Order Now

FRAT Mascot Image

For information on autism monitoring, screening and testing please read our blog.

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