You are asking this question at midnight. The house is quiet. He is asleep. You are on your phone doing the thing everyone tells you not to do, which is Google medical questions about your kid at midnight. Nobody is answering you because the pediatrician's office does not open until 8am.
This article is written to give you the honest, calm answer that you would get from a good pediatrician if you could call one right now. In most cases, the answer is no. But there are three specific things worth checking before you decide to relax, and three more that would justify picking up the phone in the morning.
The five-minute check
Before deciding whether to worry, get these five numbers together. If you can, write them down. Having them all in one place changes the answer from "I don't know" to "here is exactly what is going on."
- His current percentile on the CDC growth chart. Not "average" or "small." The specific number. Your pediatrician has told you this. If you don't remember it, call the office and ask.
- How much he has grown in the last 12 months. Roughly. Two inches? Three? Half an inch? You can eyeball this from photos on his last birthday.
- Dad's adult height. To the closest inch.
- Mom's adult height. Same.
- Any family history of late blooming. Was dad short in middle school and then had a growth spurt? Uncles? Grandfathers on either side?
Once you have these five, most of the worry either evaporates or focuses onto something specific you can actually do something about.
Three things that mean you can probably relax
1. He is tracking his own growth curve
Even if he is at the 15th or 20th percentile, if he has been consistently at the 15th or 20th percentile for years, he is following his personal genetic trajectory. That is completely healthy. He is not "falling behind." He was never at the 50th to begin with.
What matters is whether his line on the growth chart goes up steadily. Not whether the line is high or low.
2. Family-height math predicts where he currently is
Use the mid-parental height formula. For a boy: (dad's height + mom's height + 5 inches) ÷ 2. Result is his likely adult height, plus or minus 4 inches.
If dad is 5'8" and mom is 5'4", the math predicts 5'8.5", range 5'4.5" to 6'0.5". If your son is currently 5'2" at age 13 and the math predicts adult height in the 5'4" to 6' range, he has plenty of runway.
3. There is a family history of late blooming
If dad remembers being the smallest kid in his class through eighth grade and then had a big growth spurt in ninth or tenth, that is one of the strongest signals that your son will follow the same pattern. Constitutional delay of growth and puberty is highly heritable.
Three things that mean you should call the pediatrician
1. His growth velocity has slowed
If in the past 12 months he grew less than 2 inches and he is not yet in the puberty window, that is worth checking. Same if his percentile has dropped by more than 2 bands (went from 50th to under 20th, for example) over a year. This is a growth curve that is bending downward, and it is worth understanding why.
2. He is below the 3rd percentile AND family-height math says otherwise
A boy at the 3rd percentile whose family math predicts 5'11" is a much different situation than a boy at the 3rd percentile whose family math predicts 5'6". The first case suggests something is limiting his growth. The second case is just familial short stature.
3. He is past 14 with no signs of puberty
By age 14, most boys have some early signs of puberty (voice changes, pubic hair, testicular enlargement). If he is 14 or older with none of these signs, that is worth a conversation with a pediatrician about delayed puberty. Often this turns out to be constitutional delay and requires no treatment, but the check is worth doing.
Most of the time, "should I worry about my son's height" has the answer "no, but here's what to keep an eye on." A very small percentage of the time, the answer is "yes, and here's exactly what to ask your pediatrician." The Growth Check tells you which one you are dealing with in about 60 seconds.
What NOT to do
- Do not buy a "height boosting" supplement. There is no OTC supplement that meaningfully increases adult height. Every one of them is preying on midnight-Google parenting anxiety.
- Do not push him to eat more. If he is not underweight, forcing calories does not add height and it does damage his relationship with food.
- Do not tell him you are worried about his height. This is well-intentioned and it does specific damage to how he sees his body. Have the conversation with your pediatrician, not with him.
- Do not compare him to his cousin, his classmate, or the kid down the street. His trajectory is his own.
The one thing to do this week
Run the Growth Check. It is free, takes 60 seconds, and gives you the same numbers a pediatrician would compute. If the check says he is on track, you can put the phone down. If it flags something, you have a specific question to bring to the pediatrician instead of a vague worry.
Either way, you sleep better tonight.