Infantile Metrics

Is. had her six month check-up on Friday morning, which meant we learned the
new set of measurements. This percentile, that percentile. Head
circumference: 35th. Weight: 28th. Length: 49th. Percentiles are a
relatively uncomplicated normative system for babies: their first (or second, after APGAR) grades.
A kind of IRE (Infant Record Exam).

Fortunately, as of Friday, Is. will now have one set of scores.
Throughout the first six months, she had two sets, each corresponding to a
different age: one actual, one gestational. Against her actual peers:
15th. Against her gestational peers: 53rd. At six months, we’re told, her
earliness starts to matter much less, and her development is now calibrated
against others born in early August. This means she’s being scored against
full-term babies. Unfair, of course.

All along, I’ve been intrigued by the scoring, but not because I get worked
up about how her head size compares (I’m probably in the 99th percentile both
for noggin and nose, so it’s reassuring that she’s not yet topping out either of
those charts yet). The intrigue, in part, involves the way the chart, onto which
the measurements are graphed, shows shaded areas–zones of risk related to
patterns of measurable development.

I suppose there is a lot more that could be said about this, but I mention it
only because I’ve been giving it some thought since Friday. It’s sort of
bizarre, on the one hand, and practical on the other. And, as Collin has
suggested to me, an expanded array of percentiles could be the conceptual basis
for one hilarious comic. But, until I can draw better, I’ll just keep it
in mind, and look forward to plotting the new evidence of growth when we let the
pediatrician tangle her in scales and rulers in another three months.