I have a stupid question re: percentiles...

AimeeL85

DD had her 4 month check-up yesterday and looking at some of her stats vs. DS' stats at that age made me wonder...

If she is 50th percentile for weight....does that mean she is 50th percentile among all other 4 month old babies...

...or does it mean she is 50th percentile among all other 4 month old babies who are the same height as her?

DH thought they might also factor in gender.  Does anyone know?

Thanks!

kjsmith9

Check out the WHO growth charts in the middle of this page:

https://www.cdc.gov/growthcharts/who_charts.htm

 

They have percentiles for babies based on gender + age, and gender + height... and they're different.  At her 4 month appt, DD was ~ 35th to 40th percentile for her weight based on height, and 50th percentile for her weight based on age. 

The pedi says he uses WHO growth charts, but always gives me weird percentiles at her appointments.  So I always come home and check for myself  

ASmallWonder

It means she's in the 50th percentile of other 4 month old girls.  The height is calculated separately and they aren't tied to each other in the way you're thinking but it's good to see the relationship so you know if you have a very tall but very skinny baby or a very short, chunky baby, etc.

ForeverEverAfter

Depends on the charts. Our public health nurse uses WHO charts and gives us weight for age, height by age and weight adjusted by height for age. She says weight adjusted for height is most accurate. She uses a computerized system though, I don't know if there's a printed chart for that.

this decaf life

I'm pretty sure it's separated by gender and weight is compared to just weight. Height to just height. Head circumference to head circumference.

My DD is like 25% in weight, 75% in height and 50% in head circumference.