Wait, How Far Along Am I?

Just as an example, at 24 weeks, some people call themselves “6 months pregnant” (apparently assuming 4w=1m). I’ll be 24 weeks on Sept 1st.

To me, six months pregnant would mean counting three months back from my EDD of Dec 22, so I wouldn’t be “6 months pregnant” until Sept 22nd.

Then you look at this chart…

… and you realize how confusing it can be.

Apparently there are three ways to calculate the trimesters and age.

The three basic ways to calculate trimesters

There are basically three ways of dividing up a pregnancy into the three trimesters; they are by:
Development,   Gestation,   Conception. They give different dates for when the second trimester begins and for when the third trimester begins. Your health care provider might prefer to use theDevelopment method, while another Midwife or Doctor may use the Gestation method.
I am sure they do that just to confuse pregnant women.  Big Grin

by Development:

This uses actual developmental stages to divide up a pregnancy. From LMP to 12 weeks the embryo develops all the major organs and becomes a fetus. From 12 weeks to 27 weeks the fetus continues developing and reaches viability. From 27 weeks on the fetus finishes development and prepares for delivery. Here the second trimester begins at 12w 0d and the third at 27w 0d.

by Gestation:

With this method you take the 40 weeks of gestation and divide by three. Here the second trimester begins at 13w 3d and the third at 26w 6d.

by Conception:

This method is where you take the 38 weeks of post conception development, divide by three, and add two weeks. Here the second trimester begins at 14w 5d and the third at 27w 3d. 

No wonder we never quite know how far along we are!


  1. haha, it's so confusing isn't it? Why can't it just be straight forward?

  2. It's actually a big pet peeve of mine when people say they're six months when they're 24 weeks. As most months have closer to 4.5 weeks, it's actually pretty far off! And the whole "pregnancy is actually 10 months" b/c of dividing 40 weeks by 4, same thing. but no, if you count from conception, you do not deliver your baby 10 months later. But maybe that's just because I'm anal and analytical 🙂

  3. P.S. cool tool!

  4. I agree that using "months pregnant" puts you way farther along than you really are… and that's why I always used it when I thought my belly was bigger than it should be :)On the other hand, when you say 24 weeks to anyone who's NOT pregnant, they just divide by 4 in their head and get to 6 months anyway.When I wanted to be honest, when someone asked, "How far along are you?" I'd say, "I'm due in September" and let them do whatever math they preferred on their own.

  5. Hilarious! I had the discussion with my Dr when I had my bleeding episodes. I was at 11w6d with the first episode and then 12w6d with the second. Here I was thinking the magical number 12 was the first trimester, but he strictly goes by the conception chart, the 38 week one. He said the second trimester actually didn't start until 15 weeks. That was kind of a downer for me. Maybe because I'm IVF, it's more accurate that way. I mean we do actually know the exact time my child was conceived, in a dish 40 miles away from my husband and me :)So yeah, you're right, there is no way to know exactly where we are…but we have an idea that we're somewhere between 5-6 months pregnant, right? At least we know the end date…or the "assumed" end date!

  6. Haha! It does get a bit confusing at times. I suppose it's a bit subjective.I tend to lean to the scale at the bottom, but that's just me. In th end, the baby's cooking and will come out when he deems it time!

  7. Holy crow, thanks for posting this. Confusing, yet enlightening. 😉

  8. Very confusing, yet so cool that you are even in the ballpark of 6 months. I can't believe how fast time is going (easy for me to say I know).

  9. Oh man I finding myself wondering how many months I am all the time. It's weird because I feel like non-preggo's understand months better than weeks (I know I did) but I never quite know how many months to tell them.

  10. It's funny to me that when someone asks how far along I am and I say 30 weeks they either know exactly what that means or they get this glazed over look on their faces and they are thinking- why is she counting in weeks??

  11. I never knew that, that's why I'm so confused when people say things that don't seem right. I think I've always thought you take the 40 weeks and divide by 3. Oh, well, I don't think it matters in the long run.

  12. I know! It's so confusing! I'm going with the 40 divided by 3 approach. I was so confused when a fellow blogger, who's due date is a couple days AFTER mine, put that she was 6 months. I was like, "Huh???" We're only like 23 weeks, how is that 6 months? And yeah, I understand how people think 24 weeks is 6 months, but that's only if every month was February. It's all so weird. I just know every day that passes is one day closer to meeting this little guy. And, speaking of which, do you know what you're having? I don't THINK you've posted your big gender reveal. When will you know?

  13. So cool to get caught up on you…been away so much. You look seriously adorable in your photo. P.s. To answer your question on my blog, we transferred the only blast we had…our shining star! Your rock star sounds well on his way. Don't let the lack of movement scare you….they have to sleep and rest lots.

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