Story update 5/31/2012: Joel Smith and his wife Silvana are the proud parents of a new baby girl, Juliana Garcia Smith, born May 23, 2012.

My wife and I have been expecting a baby girl soon—very soon, in fact, as in “Will this be published before the baby is born?” soon. The due date given was May 19, but we stat geeks know that a point estimate just isn’t good enough. We want probability intervals that reflect the uncertainty in the data.

I found a chart that lets me know the number of babies born to “spontaneous labor” by each week of pregnancy, but I’m interested in more precision than just the week. I converted the data to days instead of weeks (for example, week 40 starts on day 280 and runs through day 286), and here it is:

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