Chris asked me in a comment yesterday about why my ticker still said 21 days when I was considered full-term. There are probably other people who might be confused. So, I thought I would do a basic run down on due dates. Hopefully this wont be too much information for any of you (ahem, Dad). I’ll try to be sensitive.
Here’s how it works. At least this is my understanding.
At your first OB appointment, the doctor gives you an EDC (estimated date of confinement). That’s an old fashioned word that we translate to mean “due date”. It is calculated out approximately 40 weeks from the first day of your last cycle. It’s kind of crazy because in about 99.9% of cases this means that according to that math you are anywhere from 1 day to 2 or 3 weeks “pregnant” before you actually are, in fact, pregnant. The reason it’s calculated this way is because there is no way to actually be completely 100% positive on what day you actually conceived without having an ultrasound done on that exact day. I don’t know who decided that 40 weeks would be considered the benchmark, but I think I read somewhere that’s the average point where most women will deliver (give or take a week or two) before the placenta starts to break down.
Isn’t 40 weeks actually 10 months? I thought pregnancy lasted 9 months. I’m so glad you asked!
40 weeks would be 10 months if all of our months actually had exactly 4 weeks in them. As it is, we only have one calendar month that has exactly 28 days. For example, I think we would agree that Jan 1- June 30 is 6 months. If we went off the assumption that each month had only 4 weeks in it, we would say that would be 24 weeks. That’s actually wrong. There are almost 26 weeks (one day shy) in those 6 months. If you think of months in those term it makes a little more sense. Also, remember, the doctor has started counting before you are actually pregnant and a due date isn’t exact science. It’s an educated guess. Does that make sense?
What’s the deal with 37 weeks then?
I’m not sure why most doctors consider 37 weeks full-term. I think it’s a combination of the fact that most babies lungs are fully developed by that time and that the due date is an educated guess. It’s usually the earliest that a doctor will do an induction if there are no other medical complications for Mom or baby. It’s also around the time when, if you go into labor, a doctor will not try to stop you from delivering. Full-term means the baby is pretty much all developed and ready to go and the doctor will no longer consider your baby a preemie at this point. The baby is just putting on extra fat. So, full-term doesn’t refer to reaching your due date. It refers to reaching 37 weeks.
I’m sure I’m missing something, but that’s the basic explanation. It’s not all that technical. It’s how my non-medical brain understands the process.
