The Path to Development- Each is Unique Knowing when to Worry (and When Not to Worry)

The Path to Development- Each is Unique
Knowing when to Worry (and When Not to Worry)

This note is about the timing of development.  Most guides for parents about development focus on the average age at which a skill is developed.  A sequence is presented, and if your infant does not attain each skill around the average age, one has to worry.  The picture presented is that development should be a smooth process, and about the same from child to child.  The implication is that anyone gaining a skill after the average age, something might be wrong.

There are profound problems with this approach to thinking about the timing of how your child develops. The biggest problem with this perspective is that it doesn't even come close to presenting what actually happens.

When we look at any individual, we see peculiarities and unique qualities to how he or she proceeds along development.  Everyone takes a slightly, or even dramatically, different approach to learning to and actually smiling, sitting, walking, and talking.  Perhaps the greatest variation is obvious in the developmental tasks of walking and talking.

Some kids go from sitting to walking in one gulp.  They suddenly get up and walk around.  More commonly, other kids will slowly reach for standing, pulling oneself up to standing, then walk holding on to furniture (cruising), let go and stand alone, then take some tentative steps, all before getting up and running around.  Still others may get to the cruising stage and then stop progressing, for a long time, finally walking freely months after starting to cruise.  Some may rush to one stage along this walking sequence, take a long time to reach the next stage, then rush again to the next.  And these variations are all in kids who turn out to walk just fine.

So, several important points to make:
  1. Variety is good not bad.  Variations in how one approaches gaining a skill almost never indicate the skill will be less than excellent.  The child who rushes to walk and the one who gets their in fits and starts both will end up walking quite well over their lifetimes.
  2. Timing is a poor predictor of quality.  When a skill begins in development, within a range, does not predict how well the skill will be done in life.  I often say, when a light switch is thrown on does not predict how bright the bulb will be. Development reflects physical changes in the brain that are like software being installed.  When you install the software has no bearing on how well the program will run.  So, a child who begins to learn to walk at age 9 months and a child who begins to learn at walk at 15 months both will very likely walk well the rest of their lives, and likely will have similar athletic prowess.
  3. Range tops average.  The average age of learning to walk on your own is 13 months old.  The range, however, is roughly 8-18 months.   That means that if you looked at 100,000 newborns and noted down the ages at which became able to take first steps alone, the average age for the group would be 13 months old, but the range, for kids who ended up walking very normally, would be about 8-18 months old.  That is, the first kid to walk probably did so no earlier than 8 months of age, and nearly everyone was walking by age 18 months old.  If you really believe the first two points, then you would have to agree, it make no difference is one attains normal walking abilities at 9 months old, 12 months old, or 15 months old.   This point is really saying, how you get there is not as important as getting there.  The choice of approaching learning to walk with caution or abandon, at a younger or older age, simply has no impact on if you will learn to walk, and walk well.  This is important.
  4. Half of all people are not delayed.  When one relies solely on the average age at which a skill is attained, suddenly half of all people have a problem.  By definition, for any skill, half of all healthy and skilled people attain that skill after the average age.   If the average age of learning to sit alone is 7 months old, half of all infants will develop the ability to sit at or after the age of 7 months old.  If we define normal as having the skill by the average age, half of all people will be abnormal.  This is a silly idea.  If half of all healthy and normally developing infants and toddlers gain a skill after the average age, it would  be wrong to designate the half that does a good job after the average age as delayed.
  5. The greatest variability in any skill is the average age most kids attain it.  This is actually a simple, but powerful insight.  Consider the skill of walking.  No one can walk when only 2 months old.  Every healthy child can walk by age 2 years old and up.  So all kids are about the same when it comes to whether they can walk much prior to and after the time they learn to do so.  A thousand 2 month olds all walk the same way- they don't.  And, a thousand 4  year olds all share the fact they walk.   But around 13 months of age, a thousand toddlers could have 1,000 different stories of how they are coming along.
So, How to Know When to Worry, and Not to Worry

The two big questions in development are:
  • What can I do to help my child's development come out as well as possible?
  • When should I worry, what signs suggest something is wrong and we should intervene.
When to Worry
Let's start by noting what any worry would be about.  Development is worrisome when something suggests that an important set of skills isn't turning out right.  In infancy and early childhood, the key set of skills we want all our children to be very good at are mainly related to walking and talking, although often we get questions about concerns about teething being late, too.

A key point here is that there is a world of difference between someone starting to do something later on, and not being able to do that skill over time.   Consider the 15 month old who is standing on her own, but not yet walking.  Let's say somehow we knew that when she will turn out to walk wonderfully all her life, starting at 17 months old, and will go on to be a star athlete.  If we knew that, we would say there is nothing to worry about in her current timing of walking.  Yes, she is starting to walk later than the average age toddlers do, but she is going to walk, run, and jump very well.

On the other hand, let's say that we somehow know that this 15 month old girl will go on to struggle to walk, a real problem in motor control emerges over time.  In that case, if we knew that, we would institute physical therapy to optimize walking abilities at the earliest age possible.

The challenge is that we don't know at age 15 months how someone will be later in life.  So we have to make decisions based on best guesses.  If our best guess is that no problems are likely to emerge, we would of course not intervene, but if our best guess is that the skill is not going to emerge normally, we do intervene.

Here are key approaches to knowing that something is wrong:
  1. Loss of a skill.  Any child who over time shows less ability to do a major skill, such as walking or talking, needs to be evaluated and seen.
  2. No progress.  Once someone starts adding skills, that process should be evident every few weeks or months.  The child who is not walking at 15 months old is less worrisome if he has developed towards that goal from 12-15 months old.  For example, if he started pulling himself to standing at 12 months, cruising at 13 months, and standing alone at 14 months, chances are he'll be walking soon.   If however, he pulled to standing at 12 months, and then nothing new has developed for 3 months, that is of concern.
  3. A current sign of illness or abnormality.  No matter when in development, if one sees your child actually suffer a problem or symptom of concern it's time to look further.  If one has a young child who is not yet talking, concerns become immediate if they have other symptoms such as avoiding interaction and eye contact to a severe degree.  The child who is not walking at 14 months old becomes worrisome as soon as a limp is noted.
  4. At some point, not able to do a skill after too much time has passed.  Keeping in mind that each person's path to development varies, so the marker of time that means anything should not be the average, but really some point in time where about 95% of kids have attained that skill.  That turns out to be a point in time known for every developmental stage.  For walking that age is 18 months old, for speaking phrases that is about 24 months of age.
  5. Making good progress from month to month is reassuring, losing progress is very unusual and of concern.

  1. Not just most, but a vast majority of children develop normally.
  2. Every person has their own path and trajectory of development, there is no single normal pathway.  Each path is as unique as each snowflake.
  3. The average age for achieving a skill in development is not a helpful guide to knowing when someone should do so.  
  4. A much better guide is the range.  That would be the earliest age we see children developing that skill, and the age by which 95% of children have the skill.
  5. When a child starts having a new skill does not predict how well a person will do that skill.
  6. When looking at your child's development, it is reasonable to start from the expectation that all will proceed normally, and wait to see signs as noted above of concern, before launching interventions.
Dr. Arthur Lavin

*Disclaimer* The comments contained in this electronic source of information do not constitute and are not designed to imply that they constitute any form of individual medical advice. The information provided is purely for informational purposes only and not relevant to any person's particular medical condition or situation. If you have any medical concerns about yourself or your family please contact your physician immediately. In order to provide our patients the best uninfluenced information that science has to offer,we do not accept samples of drugs, advertising tchotchkes, money, food, or any item from outside vendors.

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