Friday, October 26, 2007
What I've Learned About the Weights and Heights of People with Down Syndome
At the DDC's Buddy Walk this year a mom asked me what I'd learned about the body measurements, weights, and heights of people with Down syndrome - based on my research and the measurement data that we'd collected to date. I shared my knowledge and observations to that point. I've recently been crunching numbers and analyzing graphs and because I enjoy this sort of thing I thought you guys might as well.
I've included four graphs in this posting, at the top. They're pretty simple, so it's easy to understand. They are the 50th percentile height and weight curves for boys and girls, with and without Down syndrome, from ages 2 through 18 years. These provide an interesting enough snapshot. The graphs of the wider bands - the 25th through 75th percentiles, and the extremes - the 5th through the 95th percentiles, are even more interesting. At any rate, the graphs are a bit hard to read in the body of the blog, but if you double click on a graph it will open in full screen mode. I'll share a few observations based on these graphs. At some later date I'll share additional insights, if anyone expresses interest.
- GIRLS HEIGHT
- Comparing the 50th percentile data, girls with Down syndrome are always shorter than girls without Down syndrome. At age 2 the difference is just over 2 inches, but the difference increases gradually each year (age 4 = 4", age 5 = 4.5", age 6 = 5"...) At about age 12-13, the "No DS" curve becomes more steep while the "With DS" curve remains gradual (and soon after begins to level off.) At age 14, the height difference is 8.25".
- At age 18 the curves have pretty much leveled. At that age, the difference is 7 inches.
- Though not illustrated on the above graph at ages 13 through 18 the 95th percentile curve of girls with Down syndrome runs nearly concurrent with the 5th percentile curve of girls without Down syndrome. So, through the teens years the tallest girls with Down syndrome are about the same height as the shortest girls without Down syndrome.
- GIRLS WEIGHT
- For ages 2 through 16, the curve for the girls with Down syndrome was below the curve for the girls without Down syndrome. However, at about age 14 the slope of the "No DS" curve decreases while the "With DS" curve stays the same. So, at 17 years old the weight is the same for both groups - 122 pounds. At that point the weight of the girls without Down syndrome has nearly leveled while the weight of girls with DS continues to rise - with no sign of leveling.
- Viewed together, the data indicate that by age 18 girls with Down syndrome were 7 inches shorter and weighed 4 pounds more than girls without Down syndrome.
- BOYS HEIGHT
- Along the entire age range - 2 through 18 years old - boys without Down syndrome were taller than boys with Down syndrome. The slope of the curves are similar for a number of years. Until age 13 boys with DS were generally about 5 inches shorter than boys without DS. At age 13 the differece jumps to 7 inches and the curves continue to diverge. By age 18, when both curves have begun to level, boys with DS are 9.5" shorter than boys without DS.
- Similar to the girls groups, in the teen years the 95th percentile curve of boys with DS are comparable to the 5th percentile of boys without DS. Though in this case the concurrence begins at age 15 (v. 13 years for the girls.)
- BOYS WEIGHT
- From ages 2 through 9, boys with DS weigh about 5-6 pounds less than boys without DS. Then, at age 10 the curves nearly meet; at that age boys without DS weigh just 1 pound less than boys without DS. The gap begins to widen again and the curve is steeper for boys without DS. So, by age 18 boys with DS weigh 12 pounds less than boys without DS.
- So, at age 18 boys with DS weigh less (12 pounds) than boys without DS. However, there is a corresponding height difference. At age 18 boys with DS are nearly 10 inches shorter than boys without DS.
- Height growth for all groups becomes gradual in the mid teen years and has nearly leveled off by age 18.
- Weight growth for both groups of boys and girls without DS becomes more gradual in the late teen years. Unfortunately, the weight curve for girls with DS continues to be steep and shows no sign of leveling off at age 18.
- All 4 of the DS growth curves we've looked at in this post are steady and gradual; there are no big leaps or dips in those curves. That's not the case with a couple of the more extreme percentiles.
- By contrast, the curves for the groups without DS - with the exception of Girls Weight - become more steep at some point in the early to mid teens. To that extent, the DS growth appears to be more predictable.
OK, that'll do it for now. That's enough fun for one Friday afternoon. (I'm really not kidding. I do enjoy looking at this stuff. That's why I created 20 slides for that file from which I pulled those 4 that I posted.) As I said earlier, I'd be happy to share more numbers and more observations in a later post if anyone's interested. Just let me know.
Hope everyone has a nice autumn weekend.