A PT’s Perspective on the New CDC Developmental Milestones
Get out your phone and find a photo, or better yet a video, of your child at 10 months old. Save it to a new album. Now find a photo or video of him at 15 months old and save it. Look at the skills he was doing at 10 months (and notice how baby-ish he looked) and compare it to 15 months. Huge difference, isn’t it?
Now imagine you are a young, first time mom with no reference point for development. You see that children should not be able to follow the direction “Come here” until 15 months old, so you are not concerned that he can’t do this at 11 months old. What you don't realize is that you and your friends were generally able to follow one-step directions around 10 months old. If you couldn’t, your pediatrician probably would have investigated why. Because you could follow simple directions, you had more freedom to explore the playground, accompany your mom on outings, and walk instead of riding in a stroller. Now, your child has lost out (through no fault of your own) on FIVE MONTHS of practice in a very normal skill for young toddlers, a skill that is vital to his safety. Five months is 1/2 to 1/3 of his life thus far. Wow.
Let’s do another one.
You take your daughter to her 9 month well check and voice your concern that she hasn’t tried to crawl at all. The pediatrician consults the new developmental milestone checklist and sees that crawling is not listed whatsoever, so neither of you are worried. Because your daughter is ready to be mobile, but doesn’t have the core strength to crawl, she begins to pull to stand. She falls when she turns her head because her primitive reflexes have not been integrated — a natural result of crawling. She stands on her toes because her core is still weak. She is delayed in cruising and walking because she never practiced weight shifting during crawling. She falls down steps and stairs because her depth perception is poor (this is developed during crawling, specifically.) She is unable to grasp a spoon and feed independently because her intrinsic hand strength was not developed, this is also done during crawling. Her handwriting suffers for the same reason. She is eventually diagnosed with hip dysplasia — a condition that occurs when the hip joint doesn’t fully develop, often because of the lack of weight bearing when children do not crawl. After a few years of PT and OT to address these issues, it is clear that the lack of crawling was both a symptom of core weakness and a cause of the future issues. You wonder why you were told that it was normal for her not to crawl, and you wonder if her developmental delay could have been avoided had you been given accurate information.
As you can see, this is not the mother’s fault, or even the pediatrician’s fault, but the fault of those who determine norms and publish resources for parents.
As you can also see, changing skills to a later age — and especially removing skills that have literally always been part of a baby’s natural development — have unnecessary detrimental effects.
If you are a mom of young kids (or even if you are not) you have probably heard about the CDC’s release of updated developmental milestones for American children, especially if you have any friends who are PTs, OTs, or SLPs. The reason you are seeing all of this (probably negative) attention about the new milestones is because they are quite different than previous publications — and not in a good way if you are like me and you work with children.
As most of you know, I am a physical therapist. For most of my career I have worked with children. I came by this career honestly — my mother is a pediatric specialist physical therapist who owns her own practice where she has treated children for over 30 years. My sister is a pediatric speech-language pathologist. Many of my friends are therapists or have children who have received therapy. This is my world. And I want to share a little of my knowledge with you today. Because it is very important that we as mothers understand the information we are given at well checks. It is important because these changes will affect the next generation of children, our children, and it is our responsibility to be well-informed so that we can make intentional decisions regarding how we raise our children. This goes a bit deeper than when our children say their first word or take their first step.
This post is a bit long, but please stick with me. I am going to show you the evidence about how American children are developing at a slower rate, what this means for their future, and why this might be happening. Besides presenting the research I will be giving you my professional opinion on the matter, an opinion that is held by many of my colleagues.
If you are strapped for time and want to know why babies are developing more slowly, scroll to the bottom. But if you are a mother, I highly recommend reading this through and sharing it with your friends.
WHY ARE DEVELOPMENTAL MILESTONES IMPORTANT?
There are two camps of thinking about child development — physical, educational, emotional, etc.
CHILD-CENTRIC: Let children grow at their own pace. Every child is different and deserves the chance to express their different-ness without intervention from adults.
PARENT-CENTRIC: Children are given to us so that we can shape them and help them achieve their greatest potential. They achieve their potential because of what we pour into them.
Like all extremes, they sandwich a happy medium. I don’t pretend to travel along that middle road at all times, but I spend enough time with parents and children, and enough time learning about child development, to have a good idea what the happy medium might look like:
Every child is different and deserves the chance to express their different-ness. However, there are instances in which a child may be ready to progress to the next developmental step but something is impeding their progress. When their inability to progress to the next milestone results in a functional limitation, then it is our job as parents to intervene and seek professional advice.
Here is an example:
Your son is 18 months old and is continually frustrated because you cannot understand any of his words. You know every child develops at a different rate, but you can tell that he has all the words in his head, just no way to express them. You wait and see if it gets better, but you find that his emotional and social skills are regressing because he cannot make his needs known. Your pediatrician consults the [previous] AAP milestones handout with you and she decides to refer him to a speech-language pathologist. The SLP shows you the research saying that at least 50% of children his age say about 50 words, and he is diagnosed with a speech delay. After standardized tests based on milestones, she problem-solves the reason for your son’s speech delay and over the course of a few months he is able to make his needs known and express affection. His emotional and social skills improve, and he gains the confidence to try new physical skills that you realize he had not been attempting before. Because of the success he had in speech therapy you ask for a referral to physical therapy. The PT also performs a milestones-based test along with other clinical tests and determines a mild gross motor delay. He is seen for six months before being seen on a consult basis according to your concerns.
This is a common example of why a neurotypical child* might be seen by a therapist. The parent’s general knowledge of developmental milestones prompted questions. The therapists used standardized tests based on milestones, along with their clinical judgement, to identify the issue and successfully help the child progress past his sticking points, leading to acquisition of other skills. (Movement, speech, feeding, cognition, and social skills are all connected. When one area is delayed, often other areas are delayed.) This example is given to show you how developmental milestones are used in everyday life.
Obviously, changing milestones to a later age would have put this child at risk for being “missed.” He most likely would not have been referred because, now, it is “normal” to only attempt 2-3 words by 18 months. This little guy probably would have eventually figured out how to use his words, but at the expense of other skills. This is why the milestones should not be changed.
*in this article “neurotypical” will refer to children who have not been diagnosed with a neurodevelopmental condition, such as cerebral palsy, Down’s syndrome, autism, etc. We are talking about children who would be expected to meet developmental milestones in the appropriate time range.
WHAT WERE THE PREVIOUS MILESTONES? WHAT CHANGED?
Here are a few examples of previous milestones per AAP’s Pathways.org compared to the most recent CDC milestones.
As a therapist I often refer patients to Pathways, by the way. As of this writing, they have not updated their website with the new milestones.
Changed from a 4-6 month skill to 9 month skill
Moves things from one hand to another
Uses consonant sounds like “da da da”
Creeping or crawling is a vital skill that should emerge between 7-9 months —> IT IS NOT MENTIONED IN THE NEW CDC MILESTONES.
Changed from 10-12 month skill to 12 month skill
Uses “mama” and “dada” meaningfully
Uses thumb and finger to pick up small object
Understands “no”
Pulls to stand and cruises
Changed from 10-12 month skill to 15 month skill
Says 1-2 words besides “mama” and “dada”
Responds to simple directions like “come here.”
Communicates wants and needs
Independent steps: several by 10-12 months —> a few by 15 months
Changed from 10-12 month skill to 18 month skill
Finger feeds
Drinks from an open cup
Independent walking has always been accepted to occur in a larger range, approximately between 13-18 months. (When I was in grad school that age range was even earlier because that’s what the majority of children were doing…) It is not mentioned in the new milestones until 18 months, the age that walking was previously considered “delayed.” As PTs we suggest intervention if they are not taking steps by 12 months, not walking by 15 months, if they did not crawl, or if they walk on their toes.
This specific change is very significant.
Changed from 10-12 month skill to 24 month skill
Uses hand movements to communicate
Changed from 15 month skill to 18 month skill
Speech: May use 5-10 words at 15 months —> Tries to say 2-3 words 18 months
Changed from 15 month skill to 24 month skill
Identifies two body parts
Changed from 18 month skill to 24 month skill
Points to familiar objects in pictures
Older skills:
Uses at least 50 words changed from 21 months —> 30 months
Uses two word phrases changed from 24 months —> 30 months
What’s the big deal if some skills are expected to happen a few months later? The big deal is that 1 month, 3 months, and definitely 6 months is a very big relative deal to babies who go from womb to walking in a span of 12 months. If you compare the rate of knowledge and skill acquisition of babies in their first year of life to any other year of life, there is simply no comparison. It’s like comparing dog years to human years. (Bad comparison, but you get the point.) Six months to you and I is not the same as 6 months to a baby.
WHY ARE THE CHANGES SIGNIFICANT?
The skill acquisition in the first 1-2 years of life are not the same as skill acquisition in adulthood, or even adolescence. For example, research shows that specializing in a sport as a pre-teen does not give any advantage to those beginning a sport at 15 — rather, it is based on their inherent skill and motivation, not when they began. (Michael Jordan didn't start really playing basketball until 15.) In other words, gaining a skill earlier or later, it did not make a difference in the long run; everyone was at the same level eventually. This thinking does not apply to babies. If babies are allowed to struggle with skill acquisition in their first 1-2 years of life without intervention they are bottle-necking their development in other areas, potentially for their entire lives.
As with everything, the following things happen on a continuum. Some children are not awfully affected by not crawling, for example, while others are profoundly affected. Again, we don’t know to what our children are prone, so we should be proactive and not take a chance on our children’s development.
Let’s look more closely at some of the changes.
Says 1-2 words besides “mama” and “dada,” responds to simple directions like “come here,” communicates wants and needs changed from 10-12 month skill to 15 month skill.
(It is important for me to say that this information is not meant to shame any parents who may discover delays in their children. My goal is to give you the best information in order to make the best decisions for your children from here on out. My own children developed at a different pace, and were even seen by a physical therapist briefly despite the positive developmental environment they grew up in. It is not our fault as parents if our children are prone to delay, but it is our responsibility to know what is normal and realize that we have resources.)
By teaching the next generation of parents that their children should not be expected to tell them they are hungry, name their siblings, or respond to simple safety commands until they are 5 months older than all the other babies before them, we are stunting their children’s intellectual and communicational growth. Children have windows in which they gain skills most optimally, develop certain emotions, and naturally begin to try new foods and new activities. Once these windows pass you have missed their most efficient timeframe in which to gain a skill. (Not that it cannot still be gained — that is the premise of my job as a physical therapist.)
Here is an example of the science of natural baby development and why we shouldn’t mess with it: At 6 months old, a primitive reflex integrates to allow baby to bring their hand to mouth and begin exploring foods. At this time their gag reflex is triggered further forward on the tongue than ours is, as a protective mechanism against choking. They also have a bit of tongue thrust that helps keep things forward in their mouths. Six months is also the time when they begin engaging their core to sit, meaning their tongues and jaws are more stable — hence they learn to move food around their mouth and chew safely. Helpful coincidence, huh? As their core stabilizes between 6-9 months, they begin to lateralize their food and become really good at putting food in just the right places to chew and not choke. Around 8 months old the gag reflex is triggered further back in the mouth, but by this time they have practiced enough in a sitting position that they know how to not choke. Isn’t it beautiful how babies develop different systems together for a purpose?
Now, if a child has been in positioning devices and hasn’t had the chance to develop their core or sit on their own, they
1. haven’t been able to fully integrate the reflex that helps them put things in their mouth safely and with coordination, and
2. they haven’t developed the core stability needed to control food in their mouths.
By the time they gain their stability enough to play with food, their protective reflexes are gone and the gag reflex has already moved back, so they are at a higher risk of choking. They may need to be on softer foods for longer which starts a whole other issue with nutrition and feeding.
The CDC is now telling parents that the normal time for babies to begin sitting is 9 months… after the scientifically normal time for babies to sit and begin to safely explore things with their mouths. This is putting babies at a higher risk of choking and is setting them up for texture sensitivities and feeding problems that can stay with them for the rest of their lives.
Can you see how simply moving the perceived normal age of sitting causes a whole host of other problems?
It just doesn’t make sense. I wonder how this forward shift in normal skill acquisition (that is not based on science, but simply a report of what children are doing today) will affect the next generation of children emotionally, physically and intellectually? I guess only time will tell.
It is not hard to look through the other skills and predict the natural progression. Things babies have literally always done at 12 months is now not going to be expected until… 24 months.
We should appreciate this information for what it is — a report on the current state of affairs — and not confuse it for what it certainly is not — normal.
That is the bottom line. But keep reading, because it is crucial to understand how we got here.
THE UPDATED MILESTONES PUBLISHED BY THE CDC …
… are based on research conducted by the American Academy of Pediatrics (AAP). The CDC funded this research and you can find all of their methods and results for free on AAP.org. Here are two quotes from the AAP research article:
“The American Academy of Pediatrics (AAP) recommends developmental surveillance and screening to identify children with developmental delays or disabilities (DDs) early, help to ensure timely interventions, and improve outcomes. Developmental screening involves the use of validated screening tools at specific ages or when surveillance reveals a concern. Diagnostic evaluations are conducted, typically by developmental specialists, to further evaluate and diagnose DDs in children deemed at risk through surveillance and screening processes.” (Evidence-Informed Milestones for Developmental Surveillance Tools, AAP.org)
“The Centers for Disease Control and Prevention’s (CDC) Learn the Signs. Act Early. program, funded the American Academy of Pediatrics (AAP) to convene an expert working group to revise its developmental surveillance checklists. The goals of the group were to identify evidence-informed milestones to include in CDC checklists, clarify when most children can be expected to reach a milestone (to discourage a wait-and-see approach), and support clinical judgment regarding screening between recommended ages.” (Evidence-Informed Milestones for Developmental Surveillance Tools, AAP.org)
Therapists agree with the AAP about the following points:
Milestones help us identify when a child is experiencing developmental delay by giving timeframes in which certain skills can be expected to appear.
While we never want to rush children to achieve milestones before they are ready, we want to identify when abnormal factors may be impeding their progress toward skills that they are ready for, but are unable to achieve because of things like prematurity, weakness, tightness, lack of opportunity, or underlying conditions.
Like the AAP, we (physical therapists) generally discourage the “wait-and-see approach” because a child may be learning a skill in a detrimental way, setting them up for future injury or continuing delay. While they are struggling to achieve a skill that they are ready for, they are unable to focus their attention and cognitive energy toward other age-appropriate skills. In essence, while we “wait and see” if they will catch up, we are robbing them of time and possibly allowing them to fall behind in other areas.
It is critical to note that the goal of this AAP study was to “identify evidence-informed milestones” to “support clinical judgment.” The term “clinical judgment” refers to the expertise of the clinical doctors (like myself) and other therapists (PTs, OTs, SLPs, etc.) I would like to point out that, to our collective knowledge, neither the AAP or the CDC utilized the clinical judgment of the experts that they claim to support when they released the new milestones. If they had, we would have had a lot to say about why telling parents that it’s normal for their children not to crawl or not to say more than 5 words at 18 months is extremely detrimental to the next generation of adults.
Stay with me. You need to understand why it matters so much that they changed the “norms.”
HOW ARE DEVELOPMENTAL MILESTONES DETERMINED?
It is crucial that we as parents understand the term “norm-referenced.” This term means that the data they collected reflects what the a percentage of children are doing at a certain age, NOT what is scientifically or historically normal (that would be termed “criterion-referenced”). These definitions are simplified, but what is important for you to know is that norm-referenced data does not take into account what has been normal in the past, only what is happening now. Norm-referenced data — such as the updated milestones — are a reflection of how children are developing right now, and they are developing at a slower rate compared to just a few years ago.
One of the main reasons I am writing this for parents is to point out that never in recorded or researched history have our children been found to develop their skills as late as they are developing them today.
“Application of the criteria established by the AAP working group and adding milestones for the 15- and 30-month health supervision visits resulted in a 26.4% reduction and 40.9% replacement of previous CDC milestones. One third of the retained milestones were transferred to different ages; 67.7% of those transferred were moved to older ages. (Evidence-Informed Milestones for Developmental Surveillance Tools, AAP.org)
Notice that the AAP tells us here that more than 2/3 of the developmental milestones were moved to older ages.
New CDC milestones are based on norm-referenced data: “Subject matter experts identified by the AAP established 11 criteria for CDC milestone checklists, including using milestones most children (≥75%) would be expected to achieve by specific health supervision visit ages and those that are easily observed in natural settings.” (Evidence-Informed Milestones for Developmental Surveillance Tools, AAP.org)
One of the reasons for the change is that they reported what was seen in the middle 75% of children, when in the past they reported what was seen in the middle 50% of children.
(Picture a bell curve. Ideally, looking at 12.5% more children above and below the median should not have changed things much, yet it did. This means that there are so many children developing skills at a later age that the middle 75% of them brought the whole average way down compared to a few years ago…)
My question as a therapist is — Was that change really helpful? Now we just normalized what used to be outside the bell curve.
Their rationalization for this was
“[Researchers] believed that using 50th percentile milestones for surveillance would not support clinical decision-making for developmental screening because only half of children would be expected to achieve an individual milestone by a given age. Using milestones that 85% or 90% of children would be expected to achieve may limit opportunities for additional screening for too many children at risk for developmental delays. A ≥75% criterion was thus agreed upon to balance informed clinical decision-making regarding developmental screening and provide opportunities to identify children at risk for delays as soon as possible.” (Evidence-Informed Milestones for Developmental Surveillance Tools, AAP.org)
Essentially, it seemed unfair to them to expect a child to perform like only half of the children their age. They believe it is better to compare them to a larger pool of children. They admit that basing results off of 35-40% more children would run the risk of missing children with developmental delay, so they took a middle road of just missing some children by basing results on 25% more children. I don’t know about you, but I would rather my children not be the ones who are now being missed…
So, just like we are removing ATC and SAT entrance scores because too many high schoolers are performing below college standards, we are lowering expectations of when our children should be acquiring normal skills, skills they have been acquiring at a certain rate for many, many years.
This. is. not. healthy. for. our. children.
Again, what used to be delayed is now going to be the normal information on the AAP handouts given to you at well checks.
If you know me as a parent, you know I am not about over-achieving and out-performing. This is not about wanting our children to “develop faster.” It is about wanting our children to develop naturally.
Instead of lowering our expectations, we should be asking why they are ok with lowering the standards? And why did the norms decrease that much when 25% more children were tested? In other words, why are children in America developing more slowly?
WHY ARE CHILDREN ACQUIRING SKILLS LATER THAN THEY USED TO?
This is the question that the AAP and CDC have failed to ask or answer. (Besides blaming it on the increase in percentage of children tested. That answer isn’t quite good enough for me.)
Are we ok with finding out that, as a whole, our children are reaching normal developmental milestones later than they ever have? Are we ok with the fact that our children might be missing out on developmental opportunities because their signs of delay will be missed?
American children who have no conditions that we would expect to cause delay — your average, neurotypical child — is developing at a slower rate than they have in the past.
Why?
Let’s look at the suggestions they give for keeping our children on a healthy progression, and we can reverse this to see what might be causing the delays. Their suggestions are the same as they have always been, by the way, and in my opinion, they are sound suggestions.
“Keep your baby active. She might not be able to run and play like the “big kids” just yet, but there’s lots she can do to keep her little arms and legs moving throughout the day. Getting down on the floor to move helps your baby become strong, learn, and explore.” (CDC)
This is great advice. Babies do not mind being on the floor. They need to feel the effects of gravity in order to develop their postural muscles for future balance and joint health. Moving against gravity helps them become more alert, aware and cognitively engaged. This is opposed to being reclined or held upright for long periods. Remember the middle road between extremes? No one loves baby wearing more than me, but babies also need time to themselves on their back and tummy, from day one.
“Try not to keep your baby in swings, strollers, bouncer seats, and exercise saucers for too long.” (CDC)
My expert opinion is to avoid swings, jumpers, exercise saucers, etc. altogether. The reason is that you do not know how much is “too much” for your baby. These pieces of equipment place them in abnormal weight-bearing positions, teaching them the wrong way to stand. This wrong way gets engrained in their very smart brains and it is extremely difficult for them to unlearn patterns that are already there. This often leads to developmental delay, and is often not addressed until they are delayed in walking. We. see. this. so. much. If you need tips and tricks for avoiding these things, please reach out. I never used any of this with my children and I would love to help you brainstorm better ways of keeping your babies safe and entertained.
“Limit screen time. For children younger than 2 years of age, the American Academy of Pediatrics (AAP) recommends that it’s best if babies do not use any screen media other than video chatting.” (CDC)
There is ample research on why children under 2 should not be exposed to screens. Not only does it affect the attention centers of the brain, but the self-control, behavioral, speech and emotional centers. Screen time for babies can indirectly cause gross motor delays as well. We did not do this perfectly, but we did avoid screens with our children until 12 months, they didn’t have daily screen time until about 18 months, and didn’t see full length movies until about 2 years. We also do not use devices in restaurants, waiting rooms, etc. Again, if you need help with alternatives to screen time let me know!
I believe that these are three significant reasons why our children are developing at a slightly slower rate.
Less Tummy Time
More positioning devices
Screen time
Prior the invention of baby Positioners and screens, children simply laid on their backs, tummies, or were held. When they were bored they did something, they didn’t watch something. They learned to entertain themselves, instead of simply being entertained. They developed at their own pace without artificial stimulation.
We as parents have two responsible choices:
We can eliminate these easily eliminated barriers to our children’s development, or
If we choose to use positioning devices and screens we need to understand the risks and be very well informed about what actual normal development is so that we can recognize when our children might begin to fall behind because of the artificial stimulation.
I’ve already seen many people become upset with the CDC for changing the milestones. But actually, it is their job to research what is going on and make suggestions based on the research. That is what they did. It is our responsibility as parents and citizens to correctly interpret and apply the information. While they could provide us with more context about the changes, I am actually thankful this was published. Now we can finally see the effects of some of the cultural changes that PTs and other practitioners have been watching slowly develop over the last 15-20 years.
My goal is always to help mothers of my generation make more informed and empowered decisions when it comes to their lives and the lives of their children. I would love to hear your thoughts on this subject and answer your questions!
Interested in a one on one virtual consult with me? I would love to answer your question’s about your baby’s development!