due date statistics

This website is pretty interesting: http://www.dogfish.org/chris/fun/delivery.html

It shows a distribution of when babies are born relative to their due date:

And this show the cumulative rates:

Mike's response to the first graph was, "Wow, a fairly Gaussian distribution!" And to the second was, "Interestingly though, 50% of the babies are delivered by sometime in week 39, not 40."

This is fascinating stuff for us statistics nerds! :)