What do growth percentiles mean?

Question

My son is on the 50th percentile for his weight but 75th for his head circumference.

I don't even know what they are - can anyone explain?

lol he does have a big head, bless him!!

He had his 9 month check today and the doctor said everything was fine so I'm not too worried, I'm sure if there was a problem they'd have told me about it .

Thanks that makes so much more sense!

cmac - he was just over a week early but he was very small at birth.

Hes also on the 75th for his length as well so I guess that means hes going to be tall lol!!!

Actually I've misread it - he's on the 50th percentile for his weight, 75th percentile for his length and *25*th percentile for his head circumference!!!

Answer 1

It means he will be a brainy lad

Take all the results and plot them along a line with 0 at one end and 100 at the other......now because we can't measure infinetly accurately we dont plot every single measurement as an absolut value or else we would have more than a hundred groups. so we choose a total value RANGE , in other words we take the largest and the smallest and then divide into 100 groups

let's take an easy example suppose we were measurng the circumference of Booger beans ( made that up!)

and we found that the largest Booger had a circumfernce of 245 cm ( they are really big these beans) and the smallest was 190 cm
Then the range would be 245-190=55cm
so each percentile (rememberber percent means by 100's) would be 5.5 cm

1st percentile 190 to 195.5 cm
2nd 195.6 to 201 cm

and so on
so the 50 percentile is the median of the range...Is this the mean average (that's the average you did at school)?
or is it the mode ( the most popular)?

Well if it is a sample of a population, then it should be a gaussian or normal distribution ( sometimes called a bell curve)

It doesn't have to be but it usually is hence NORMAL distribution.

the majority of results in a normal distribution cluster around the 50 th percentile ( don't get confused with percentages )

Without knowing the curve, a rule of thumb would be 2/3 rds of all the values occupy the middle 1/3rd of the range

In English; most kids (2/3rds)will be between 25th and 75th percentile.

Please understand 75th percentile IS NOT 75%, statistically speaking the number of values in the 75th percentile will be equal to the number of values in the 25th percentile
( assuming a perfectly normal distribution)

PERCENTILE ..divided up into a hundred groups of values IT IS NOT A PERCENTAGE

Answer 2

I think they're of limited usefulness like BMI. All it tells you is that your daughter's growth is not typical but it doesn't tell you why. She could be malnourished or it could be genetics. I have my records from when I was a baby and my daughter tracked my growth almost identically for the first 2 years. She was born in the 50% or height and weight and by the end of the first year was down to 10% for weight and 90% for height. A lot of pediatricians would be alarmed at the change in her percentiles, but my growth chart showed I did the exact.same.thing. I came armed with my information to my daughter's 12 month appointment and the ped looked at me, shrugged and said "I'm not worried. There are worse things in life than being tall and skinny." If a child drops percentiles dramatically, then it's worth looking into why but the percentiles alone don't necessarily mean there's a problem.

Answer 3

Percentiles are 'created' when large scale studies are done on thousands of babies who are at a certain age.
They measure every single baby at each age, and plot their measurements on a chart.
A sufficiently large number are measured that these measurements can be seen as indicative of the general population.
Then when you take your baby in to be weighed, and the weight is 50th percentile, what that means is that 50% of babies in the original study had a weight that was equal to or less than that weight. The other 50% had a weight that was more than that weight. So the 50th line is really an average line. The 75th suggests a larger than average measurement.

Answer 4

Growth percentiles are just a guide of how much the average child that age weighs, how tall they are, and how big their head is around. It's just the averages for children of the same age. If your son is in the 50th for weight, that means 59% of kids his age weigh less and 50% weigh more. 75th for the head circumference means 74% have a smaller head and 25% have a bigger head. It does NOT mean that 50% have the same weight and 75% have the same head circumference. Your sons measurements seem very healthy. I wouldn't worry about him at all. Perfectly normal.

Answer 5

Out of 100 kids his age half weigh more and half weigh less. out of 100 kids 25 have larger head circumference and 75 have smaller heads. Your doctor will measure his growth on these charts at all of his well checks. If the doctor isn't concerned then you shouldn't be either. For the most part a child should stay close to the same percentile. For instance if your child is in the 50th percentile for height and weight and suddenly he is in the 5th percentile then that might indicate a problem with his growth.

50th percentile is not underweight. And it is not failure to thrive. I had a child who was underweight, and she didn't measure on the chart at all. The 50th percentile is average.

Answer 6

Growth charts are just a way for us to keep up with how our children are growing and how they compare to most other children. If you look at one you'll see there are curves drawn representing the different percentiles. The goal is for your child to follow one of those curves, not necessarily exactly, but if his wt is at 50% now(Which means he's very average) you'll want him to stay at that. It represents gradual but consistant weight gain. If he suddenly goes up to the 90%, then a doctor would worry that he's overeating or his metabolic system is working wrong, if he suddenly goes down to the 5th, he might be classified as Failure to Thrive. As for his head, it's larger than 74% of children but smaller that 25%. I wouldn't worry, as long as it's nice and round, he'll grow into it. Small heads usually indicate brain development is not what it should be.

Answer 7

Percentiles are a statistical term and give you some idea of how your baby's size, weight etc. compare to other babies. In brief if your baby is at the x th percentile for weight then x percent of babies at the same age have the same or lower weight.

Answer 8

He He... your kids got a big head. Bet that was fun delivering :-)
Our latest is on the 2nd percentile, which means only 2 percent of babies of this age are smaller than he is. But then, he was prem, so it's all okay.
It's amazing how you keep thinking he's getting bigger so quickly, but then you find out that he's still on exactly the same percentile, so actually he's just normal.
I always look forward to finding out what "score" the health visitor gives him.

Answer 9

he is right in the middle on weight half the babies his age are smaller and half are bigger.....his head is a little larger than most.but big heads on babies are normal (was he a preemie?, my daughters head measured bigger than her other measurements till she was 2) the thing is its just a guide as to where they are compared to other babies..usually the doctors are more concerned about how their own measurements match up......for instance one of my kids was 60th percentile for height and 75th for head...but only weighed in the 10th percentile so was classified failure to thrive and had to have blood work and stuff to see if i was actually feeding her or if it was something health related (turns out it was her kidneys) your son sounds like hes perfectly fine though to me congratulations !!

Answer 10

I'm no expert but... It means a kid should be a certain height and weight at a certain age. If he is too small or underweight or too big, he could have a number of problems . Or just be slow in development. They might give a kid growth hormones to make him grow. Some kids already have a hormone problem and grow too tall too quickly. Then they give them something to slow them down. Your doctor should explain more things to you. It sounds as though your son is underweight for his age. He is failing to thrive. And his head is a little undersized as well. What do they want you to do? Change his diet? See a pediatric endocrinologist? Someone should be recommending a specialist or some lab work or something.