How many months along are you anyway?

Two questions I often get are the above one, and, "why do they track in weeks?"

In the world of a pregnant woman, each week is a momentous step that culminates in a 40 week adventure (give or take). Doctors track pregnancy along this time line because something new happens each week. This is especially true in the very beginning, when important hormonal levels can leap from day to day, as the fetus quickly develops into something that represents human form.

For example, in this ultrasound from 7.5 weeks, Short Stranger barely registers (though in the video we did get to see his heartbeat!). This is the moment when the technician looks at you and says, "he/she pretty much looks like a bean."

But two weeks later, at 9.5 weeks, he has a head and body! Pretty cool, right?
All very exciting, but for the rest of the world, a woman is pregnant not forty weeks, but NINE MONTHS, right?

So how to make the conversion from weeks to months? This is trickier than it might seem, since each month (save one) is comprised of a more than four weeks. Thanks to the fabulous internet, though, there are several websites with week-to-month conversions. According to these calculations, at week 26, I was 5.98 months along, or ...almost exactly 6 months prego.