Centiles and over/underweight children.

[Baystard]

Can anyone explain how often are the centiles updated, and what impact do the increasing number of overweight children have on the usefulness of centiles?

DS is high centiles for height, and low centiles for weight. According to conventional wisdom this apparently means he's thin for his height but I think his weight is fine - he doesn't look thin, he just isn't a chubby/fleshy build. He eats well, has a good balanced diet, is very active and in good health.

Surely if the number of overweight children is increasing, which understand it is, then this would skew the centiles and make the slimmer children appear lower down? AFAIK centiles show where the child is relative to the rest of the population.

DD2 is 90th for height but 50th weight and her dietitian says this is fine as it is consistent for her.

DS is high centiles for height, and low centiles for weight. According to conventional wisdom this apparently means he's thin for his height but I think his weight is fine

I dont think it necessarily works like that. Say someone is 90th centile for height they are tall as only 10 out of 100 would be taller than them. If they were also 90th for weight they would probably fall into the overweight category as only 10 out of 100 would be heavier than them.
I think generally for most healthy weight kids especially as they get past the 'puppy weight phase their height centile will be higher than their weight centile.

I work in child health. Don't think the centiles have been updated for a while but it shouldn't matter as if you divide their weight by height squared to get the BMI then look up the BMI centile charts that will let you know if they are under/overweight. I remember a nurse telling me once my son was overweight as his height and weight were both on 98th centile. Complete nonsense as BMI was fine.

I believe the NHS charts are based on the WHO growth charts. On the WHO website it says they were last updated in 2013 so won't consider any changes in the average since then.
I've always been told as long as they generally follow their own lines & there are no other concerns there's no reason to worry or overthink it?

Thanks everyone.

He definitely follows his own lines, he's always been active, slim and fairly tall.