Due dates

The Snowbound Herpetologist is expecting a baby!
Her due date is Monday, December 9th 2013.

we predict that she will have a
Girl!
on
Thursday, December 5th 2013
at
12:24 pm
weighing
4140 g ~ 9 lbs, 2 oz

Get your prediction at Spacefem.com

OK, sometimes totally random (yes, these are values picked randomly from some distributions, not real predictions!) widgets are fun :)  But my god, I hope the baby isn’t 9lbs even when early, yikes!  At least we now know that the "predicted" gender is correct.

In his quest to find data on the distribution of natural parturition dates relative to the estimated due date, husband pointed me toward the spacefem website.  Here, besides nerdy science stuff, you can calculate probabilities of when you’ll have your baby given your due date, all based on real data.  There’s actually not as much variability as one might think, and moreover (surprisingly), inductions probably don’t have a major effect on this distribution.

The reason we are calculating this is that my parents will be flying out to the North Country and are hoping to catch the birth.  Realistically, the *right* thing to do would have been to have them schedule the trip for after my last possible day of pregnancy (they’ll induce me on December 23rd, no bargaining, if I haven’t done it myself by then) to ensure that there is, in fact, a baby to see.  However, that’s the holidays and school break, and they weren't able to get reasonable ticket prices until maybe mid-January, and really, they want to hold a newborn.  So they’re coming earlier and leaving on December 17th.  What’s the probability that they’ll miss the birth completely?

Not trivial, as it turns out.

Here are the cumulative probability curves for my “official” due date of December 9th.  Even using this date, there’s more than a 20% chance that I still won’t have gone into labor by the day my parents head home (intersection  = 0.79).  Again, you'll probably want to click on the graph to enjoy it in its full (less pixelated) glory.

To make matters worse, all that temperature charting that I did strongly suggests that my LMP-calculated due date of December 9th is incorrect, and that my more accurate ovulation-calculated due date is actually December 12th (or maybe even 13th).  However, midwife says December 23rd induction date is etched in stone (42 weeks from LMP), so it won’t change.  But with this more accurate due date, the entire curve shifts downwards and the probability that my parents miss the birth jumps to 30% (intersection = 0.69).

I’m not sure which to be more concerned about - the pretty serious likelihood that my parents totally screwed up their travel plans or the pretty serious likelihood that I will have to be induced.  I guess the one bright spot (??) is that no matter what, the baby will be born before Christmas?