The Baby Spike

visualizing when babies are born for the Scientific American

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Why Are so Many Babies Born around 8:00 A.M.?


April 2017


Graphic Science page in Scientific American


R, Illustrator, D3.js


Time of day & day of week data from CDC & the minute of day from FiveThirtyEight (which got it from the Social Security Administration)


The three radial line charts show the average number of babies born across different time frames; from weeks, hours and even down to the minute. The yellow line represents the average number of babies born. If the line is above (the area is colored red), then at those times more babies than average are born. Vice versa, if the line is below (the area in blue), less babies than average are born. Looking at the “per week” chart, the deviations from the average are very shallow, but the more granular the time frame, the bigger the spikes and dips. This reveals how scheduling & intervention in births plays an exceptionally important role on the exact time when a baby is born. People have much more influence than expected!


During OpenVisConf 2016 Zan Armstrong gave a great talk titled Everything is Seasonal. Several months later, during the start of 2017 Zan reached out to me and asked me if I wanted to collaborate on creating a visualization for the Scientific American about one of the topics Zan discussed in her talk: when babies are born in the US.

The data was available on several layers of time-granularity. From the numbers born per week, per hour and even down to the minute. There were several interesting seasonal trends going on that we wanted to point out; even though people think that they have a lot of say when babies are made but not when they are born, it seems that with the current technological advances such as inducing births and c-sections, we have a lot more to say about when babies are born than we might think.

We quickly moved towards using circular charts due to the cyclical nature of the time frames we were looking at. Another important aspect was the yellow average line, which is the same size in each of the three circles. This makes it more clear that the deviations from the mean are only small for the weekly totals, but are literally off-the-chart for the minute totals.

The final visual appeared in the July issue of the Scientific American, and Zan also wrote a more extensive blog post that dives into the differences between types of births (natural, induced, c-sections), besides the time aspect. With my Astronomy background I always have a love for visualizing scientific topics, and being published in a magazine such as the Scientific American is such an honor, I’m extremely happy and grateful that Zan reached out to me to work together on telling this story.

You can read a much more elaborate account of the design process in my blog post