Thursday, August 10, 2006

What I don't get

Here's what I don't get about the Center for Disease Control's growth charts that pediatricians use to measure children: both my kids are about in the 70th percentile for height and 50th for weight. Now, that's relative to other children their age, right? So, what does that really tell me about whether they're at healthy weights? (BTW, I don't need the chart to know that they're healthy. They look fine.) But what if I did need the chart?

The Harvard study, published in the July issue of the journal Obesity, looked at extremely chubby infants less than 6 months old. Their weight adjusted for height placed them at or above the 95th percentile on standard growth charts, a cut-off point the researchers set for being overweight.

A 6-month-old baby boy just under 27 inches long - an average length - would weigh about 17.5 pounds at the 50th percentile and more than 21 pounds at the 95th percentile, according to the growth charts.

The research examined data for more than 120,000 Massachusetts children up to age 6, but its most notable results have to do with infants. Previous research has documented a sharp rise in the percentage of overweight preschool children without separating out results for babies.

The data showed that in 1980, just 3.4 percent of infants less than 6 months old were overweight. By 2001, it was 5.9 percent, and researchers think the trend has continued since.

Are heavier peers skewing the data, so that 70th percentile today might have been the 60th percentile ten years ago?

Or should I have worked harder to bring my 'D' up to a 'C' in college statistics, so I could have dropped the class altogether and saved myself from these types of questions?



Anonymous luther said...

The really upsetting and outrageous thing about these charts is they don't give a percentile rating for "cuteness"!!!

8:15 PM  

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