Do Smarter Babies Walk Earlier? / by Methods Man

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Do you remember when your little baby took her first step? How about when she sat without support?  How about standing with assistance? Yes, for many of us these "milestones" are not exactly burned in our brain, but a new study from the journal Pediatrics suggests that some of these milestones may be really important – not just for baby journals, but for childhood development. For the video version of this post, click here.

Here’s the deal. We've known for a long time that kids with severe developmental disabilities in childhood seem to meet some gross motor milestones later than expected. But that's looking at an extreme case. The question these researchers had was whether delayed gross motor development would associate with later childhood development in kids without developmental delay.

To answer this question, they turned to the Upstate KIDS study, a prospective cohort study of over 6000 babies born in the New York area.  The study focuses only on 501 of the children though – a subset who agreed to a follow-up examination at 4 years.  So, if you’re keeping score, we’re already looking at a group that is not representative of the population at large.

Based on logs the mothers kept, the researchers looked at when the child achieved certain gross motor milestones like walking. They looked at 6 milestones in all, and compared them to the total developmental score at four years of age. The findings were… subtle.

After adjustment for factors like maternal age, prematurity, and others, there was a statistically significant association between one of the six milestones - later standing-with-assistance and total developmental score. That total score is driven by 5 subcomponents, and when those were analyzed individually, later standing with assistance was associated with worse adaptive and cognitive development.

Similar results were seen in the subset of kids with no developmental disability – the subset, which, speaking editorially here, really should have formed the primary analysis of this study.

So… ok… should we panic if our kids aren't standing and walking like a bunch of little Rory Calhoun's? I'm not ready for that yet. For one, the authors don't appear to have accounted for the multiple comparisons evaluated here – so the marginally statistically significant result has a pretty high risk of being a false-positive. Second, it's not immediately obvious what you would do with a kid who stands with assistance 2.1 months later than the average. Stand them up more? Send them to a neurologist?

In the end, we’d end up giving moms and dads just one more metric to worry about in a world obsessed with measuring kids' performance at every turn. Or every step.