what's in a due date?

after finding out your pregnant, the next super exciting news is when will baby arrive??  so you look at your calendar or maybe you have to think back a month (or 2 or 3) to find out when you last had your period.  then you count 40 weeks...that's when baby will arrive.  right?  ummmm, not so much.  first off...this is a bit of semantics but technically what you've just arrived at is your estimated due date or your guessed due date.  a due date is often perceived as a deadline, when something is over.  your library books have a due date...that's set in stone.  if you have a paper or a project you have a due date or deadline for when it must be completed. 
i like the phrase 'bun in the oven' because i think it helps wrap your mind around this idea.  a due date is concrete.  however, when you are baking they give you an amount of time to bake something but sometimes you need to pull it out a few minutes early or let it cook a few minutes longer.  even the same recipe, in the same over can vary from one day to the next.   that's how we need to look at due dates.  not as a deadline to meet but as an idea of when baby will arrive.   the window is really 38-42 weeks.   there have been lots of studies that prove the average gestational time is 41 weeks 1 day. 
in my first pregnancy, my original due date which was set based on my last period was january 28.  when i went in to the dr, she did an ultrasound and said baby doesn't look that old.  so a new date was given of feb 12.  i was actually charting at the time so i went and looked and sure enough...based on everything i had charted indeed feb 12 was a more accurate date.  baby came feb 10.  when she was ready to be born.  now in my second pregnancy, i am writing this on what has been given as my due date.  i wasn't charting but i did know my last period, so we at least have a general idea of what to work with since i declined ultrasounds this time around.  (perhaps a post for another day)  baby is not here and i'm fairly confident it will not arrive in the next 4 hours to make it today.  baby will come when baby is done growing in mama's belly. 
it's amazing how much emphasis we put on this date.  as if it's a concrete, unchangeable, exact date.  it's not.  nobody knows when labor will begin and when baby will be born.  yet we are expected to act/react on this date.  today i met a woman who asked when my due date was (by the way, a question i hate based on everything i've said so far) and i said i was 40 weeks today.  her immediate next question was "when are you going to be induced."  i said i'm not, we'll wait until baby knows it's time.