Today is officially 39 weeks. Making great progress. I lost a tiny bit of weight since last week, but still in the normal range.

When I say “officially” 39 weeks, that doesn’t actually mean anything particularly useful. Once you discover your pregnancy, and go to the doctor, one of the first things they ask is what is the date of your last period. They determine your due date based on that. Now, if you have a fairly rudimentary understanding of women’s bodies, you’ll know that you are not pregnant during your period, and you can’t then get pregnant until roughly 11 days later, during ovulation. At that point, it really is guesswork unless you’ve been charting (that is, obsessively and meticulously tracking your period, your temperature, your ovulation, and the days you have sex) (I recommend the app Fertility Friend for this, by the way), and even then, conception doesn’t happen during sex. Sperm can hang out for like 3 days – cruising around, not asking for directions, taking wrong turns, napping, etc. Anyway, the way we currently calculate due dates is a complete stab in the dark, and that’s fine. Unless you’re induced, you’re not any more likely to deliver on your due date than any surrounding day. The due date comes with a “plus or minus 2 weeks” caveat. However, this is the standard way of measuring pregnancies, so we have a lot of data to be pretty confident that measuring your due date from the first day of your last period is going to be enough right.