Pregnancy "progress" is confusing

For anyone who hasn't been pregnant yet...this post is for you. Tracking how far along you are in your pregnancy is confusing. Let me explain.

We all know that pregnancy is divided into 3 trimesters. I assumed each trimester was made up of 3 months, making my pregnancy a total of 9 months. I was wrong. On many accounts.

First, take the concept of "months" and throw it away. A month varies in length--from 28 days to 31 days. This measurement simply will not do in the "exact" science that is pregnancy (I roll my eyes sarcastically here.) Pregnancy progress is counted in weeks.

Second, pregnancy can be up to 42 weeks--not 36 weeks (that is, 4 weeks in month for 9 months). A full-term pregnancy is actually anywhere between 37 and 42 weeks, so we're looking at 9.5 to 10 months of pregnancy action.

With me so far?

Third, when you finally can find out you're pregnant, some weeks have already passed. So, how do know when to start counting the weeks? I'll let the doctor explain this one to you, but here's another fun tidbit for you. You actually have to count week 0. I can hear the "huhs?" now. So, here's how I understood it. When a baby is born, we don't say, "Oh the baby's a year old" right? We start at zero. Then, a week after the baby is born, it's a week old. You track your pregnancy the same way. Understanding this little fact makes reading those pregnancy books so much easier--trust me.

Fourth--I still don't get this one so I won't explain it--is fetal age, which is two weeks behind the week you're in. So, if you're 8 weeks along, your baby has a fetal age of 6 weeks.

So, there's your pregnancy math lesson for the day. And in case you're wondering, I'm now 12 weeks pregnant (not 3 months) and still in my first trimester.