They exist, yes.
I wish they didn't. I wish there were no growth charts, because they encourage people to measure the wrong things for the wrong reasons and then compare them to irrelevant data.
The child needs to be growing, in height, weight or head circumference --unless sick-- pretty much all the time. That was, to make it clear, an OR, not an AND. In SOME way, the child needs to be growing pretty continuously --but normal human growth is not a straight line at a 45 degree angle. Normal children grow a bit taller, get a little rounder, grow their heads a bit, get a little rounder again, get taller... all while holding pretty stable in the other two metrics.
If the child is in the 3rd percentile on any chart, it only means that in an average (mid-western, germanic) group of 100 kids the same age, 97 of them are -er than her (taller, heavier, bigger heads) ... not that she's under- anything. Someone has to be.
at 3:14 PM on Nov. 15, 2010