Project

Ups and downs of baby weight

Data science · Data Visualization · R Shiny

As a new parent and a friend of new parents, I’ve come to know that baby weight weighs on the minds of parents. Especially so if baby weight dips well above or below the middle of the trajectory curve shown to you in the doctor’s office on regularly scheduled check-ups.

But who are these curves based on? There seem to be a few variants of these curves, each from a slightly different sample. A leading source is the WHO, whose data are from the Multicentre Growth Reference Study (MGRS), conducted between 1997 and 2003 that tracked 8,500 children across six countries — Brazil, Ghana, India, Norway, Oman, and the U.S. This sample reflects a diverse gene pool, cuisines and diets, and cultural norms around raising children. Its diversity is a strength.

This calculator (built in R with shiny) uses the WHO data - which are publicly downloadable here - to help visualize weight against the percentile norms at home, away from the doctor’s office. (Later versions of this tool may allow for entering and tracking of multiple weights, allowing for tracking over time.) It also provides some context, referencing differences to other percentile categories. This calculator also lets you see how even small changes in weight - which may be within the bounds of the original measurements themselves - can change weight percentiles. You can also use it to see what percentile a child may be at a future date (say a second birthday) if they remain at their current stature.

Outcomes

Although it is tracked from birth, weight is only one measure of health. And one measure of development. So while weight alone doesn’t tell the full story, but visualizing it this way can help parents ask better questions and notice meaningful trends.