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Original poster

To not understand my child's bmi and weight centile

30 replies

PinotAndPlaydough · 20/12/2015 22:42

My daughter is 4 and is currently being seen by the paediatric department she's had a consultation and I've recieved a letter from them, part of which has documented her height, weight and bmi.
The letter says that her weight is 30.6 and on the 49th centile yet her bmi is 16.5 and on the 52nd centile. Her height is 136.4 and on the 44th centile (so presumably just below average).

I'm so confused is her weight slightly below or is above average as her bmi is over the 50th centile (I've written centile that may times now it sounds like a nonsense word). Confused

OP posts:
theycallmemellojello · 20/12/2015 22:47

I think it means that her weight is slightly below average for her age (49%), but because her height is even more below average for her age (44%) the height/weight ratio is slightly above average for her age (51%). I am sure they would let you know if there's anything to worry about, so I wouldn't lose sleep about 'averages'!

Jesabel · 20/12/2015 22:49

BMI takes account of weight and height, so her BMI is slightly above average for a 4yo, although her weight and height separately are slightly below average.

jamhot · 20/12/2015 22:53

If there were 100 girls of your DDs age lined up in order of weight from lightest (1st centile/position) to heaviest (100th centile) your daughter would be pretty much in the middle, at position 49. It's a smidge on the light side, but probably not noticeably different to the girls next to her.

If those girls were then lined up in height order from shortest (1st centile) to tallest (100th centile), she would be position 44. Again, close to the middle but a smidge on the shorter side.

Same girls lined up by BMI (weight compared to height), she would be position 52, in the middle again.

Does that make sense?

Original poster
PinotAndPlaydough · 20/12/2015 23:00

Thank you. I have been over weight all my adult life and although I'm loosing it slowly I've worked hard to make sure that my children have a healthy outlook on food and exercises. I think the 52 panicked me a bit although obviously is not hugely over.

OP posts:
lougle · 20/12/2015 23:04

Her weight is about average and her height is slightly below average. So she is very slightly heavy for her height. Or, alternatively, she is ever so slightly short for her weight.

But 'normal' BMI is anything from 5th-85th centile so she is completely normal.

AuditAngel · 20/12/2015 23:07

Ignoring the centiles, if your 4yo is 134.5 cm tall, then she is very tall, as my tall 8yo is 135 cm and my 11yo is 140cm.

Checking DD2's red book, a 4yo with a height of 134 would be above the 99.6th centile

jamhot · 20/12/2015 23:10

Great. A BMI centile of 52 is nothing to worry about at all.

This reminds me of the old comedy tv show 3rd Rock From The Sun, where some aliens pretend to be human. There is an episode where it is noticed that everything they do is perfectly average (so 50th centile!) according to statistics, and they stick out because of the effort they have put in to appear normal and average.

Your daughter sounds healthy and average to me and you're doing a great job. Numbers that do not perfectly match are to be expected. Smile

BertieBotts · 20/12/2015 23:11

Completely normal and not at all a cause for concern. Don't worry!

AnyoneButSanta · 20/12/2015 23:13

Imagine three adult women.
Let's say they're all 10 stone and that's average weight so they're all 50th Centile.

Annie is 5'5", 50th centile for height
Bonnie is 5'3", 40th centile for height
Cindy is 5'7", 60th centile for height.

Although they all weigh the same, if you look at them, Bonnie will be a little bit fatter looking than Annie, and Cindy will look slimmest.

Annie might have a BMI on the 50th centile, Bonnie's BMI would be a bit higher than that and Cindy's would be a bit lower.

But the differences in the numbers involved in your DD's case are tiny. Centiles are bunched up very tightly for children, and their weight and height sometimes change at different times. The difference between your DD's 3 centiles will fluctuate over the course of a month or indeed a day. The numbers all make sense and are all completely fine.

furtivefeline · 20/12/2015 23:15

Are those measurements in cm and kg? I was around that size as a 8 or 9 year old. And my average size 3 year old is less than half that weight and over a foot shorter.

Original poster
PinotAndPlaydough · 20/12/2015 23:19

Thank you, it's reassuring to hear it's all average.
Maybe there was a typo with her height, she's definitely not very tall, she's about the same as the other children at her preschool. I work in ft and inches so I'll need to convert it.

OP posts:
Original poster
PinotAndPlaydough · 20/12/2015 23:29

It doesn't say what they are in, she wears 3-4 or 4-5 clothes and doesn't look overweight to me (can still see her spine and ribs)

OP posts:
DefiniteMaybe · 20/12/2015 23:33

It must be a typo my dd is 4 and 104cm which I think is about 50th centile for height, my ds is 7 and 91st ish centile for height and is about 130cm.
If she's 4 and wearing 3-4 and 4-5 clothes she sounds exactly the "right" size.

Original poster
PinotAndPlaydough · 20/12/2015 23:36

I'm was going to call them anyway as they have spelt her name wrong and put down the wrong doctors surgery so I think I will query it then.

OP posts:
mydutifullaunderette · 20/12/2015 23:49

Yes, those heights and weights have got to be typos! Guessing perhaps the paed dictates letters and there's been more than one error in transcription? Or they've sent you a letter about the wrong child, since it has a different name and GP details... My LO is also four - 105 cm (50th-75th centile) and 17kg (50th centile). I hope you find out the real numbers soon. Going by your own description, you already know she's similar height to her pre-school peers and wearing age-appropriate clothes sizes, so unlikely to be any related issues hopefully.

SummerNights1986 · 20/12/2015 23:51

Height is definitely a typo!

Ds2 is about 115cm, 5 and 8 months, and that's pretty much bang on the 50th centile for his age.

Ds1 is massive for his age (7 and 11 months) and is much taller than all of his classmates...he is above the 99.6th centile and 142cm.

Your dd would be head and shoulders above her peers at that height, more in line with the Year 2's.

Mmmmcake123 · 21/12/2015 00:04

Both of my dc were in the higher percentiles but height and weight matched which meant they were not overweight for their stature. I think that is the point of percentiles, as long as a child is not dramatically different in the height percentile in comparison to weight, they are growing as expected.
If a child was on the 50th for height but 95th for weight that's a concern. If 30th for weight also a concern.
I always looked at the height percentile first and then checked the weight percentile was thereabouts.

Mmmmcake123 · 21/12/2015 00:05

Neither of my dc were given bmi results. Make sure you check height percentile first xxx

redstrawberry10 · 21/12/2015 00:23

I have a reasonably tall 7 year old dd and she is 134. if your 4 year old is that tall, there is no way you would describe her as not tall. So, that is most likely a typo.

but the calculated bmi is correct for those figures. i don't know what bmi is normal for children, but for an adult that adult would be considered underweight.

SummerNights1986 · 21/12/2015 00:41

I'm completely confused by how weight and height centiles tie in with the BMI centile. Height and weight centiles are easy, I get what they mean.

DS1 is 7.11, weight 72lbs, height 142cm. He's above the 99.6th centile for height and on the 98th for weight. Obviously big for his age but technically taller than he is heavy (just) in comparison to his peers.

He's on the 61st percentile for BMI. How? How can he be on one of the higher BMI percentiles when technically he's 'light' for his height (as at a lower percentile).

If 60% of kids have a lower BMI than him, does that mean that 'generally' there is a greater difference in a childs height and weight centiles, with height being higher? That doesn't really tie in with the whole 'obesity epidemic' stuff does it?

pilpiloni · 21/12/2015 01:01

She's not overweight. Her bmi is two percentage points above bang on average. A big lunch could cause that, it's not an exact science!

Children are only considered overweight when they hit the 80th centile

christinarossetti · 21/12/2015 01:08

If 30.6 is kilos, then yes that's about average for a child of that height, bit that would be a very big 4 year old.

Both figures are higher than those of my 8 year old.

Sounds like you've been sent another child's data.

Mistigri · 21/12/2015 06:01

As the PP said, those are not your DD's measurements, they have made a mix up and you need to contact the hospital (some other parent has received your DD's letter).

Those figures would not be anywhere close to the 50th percentile for a 4 year old!

But FWIW, you need to not get too fixated on the exact percentiles. It's difficult to measure height (and therefore BMI) very accurately in young children, but what you can say about a child whose height, weight and BMI are all between the 44th and 52nd percentile is that she is an average size in all respects.

sneepy · 21/12/2015 07:17

My 7 yo was recently weighed & measured at 119cm & 21.7 kg. She is hovering around the 25th centime line so I'm not sure those measurements can be correct.

sneepy · 21/12/2015 07:58

*centile

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