Trimester breakdown

Just a quick post about the breakdown of trimesters, months, weeks—which I have found to be particularly confusing, because I’ve used various baby books, baby planners /journals at this point. I am following the Mayo clinic’s breakdown of the trimesters, which shows that a pregnancy actually lasts more on order of 9 1/2 months—or 10 months, if you count the two weeks prior to conception.

Here it goes:

First trimester: 

Month 1 (weeks 1 – 4)

Month 2 (weeks 5 – 8)

Month 3 (weeks 9 – 12)

Second trimester:

Month 4 (weeks 13 – 16)

Month 5 (weeks 17 – 20)

Month 6 (weeks 21- 24)… I’m in week 22 right now.

Third trimester:

Month 7 (weeks 25 – 28)

Month 8 (weeks 29 – 32)

Month 9 (weeks 33 – 36)

Month 10 (weeks 37 – 40)

trimesters 2trimesters

It took me a long time to get this breakdown straight. Particularly since I bump into other breakdowns starting the third trimester at 27 or 28 weeks—as much as three whole weeks later than this breakdown. Hmm.

Anyway, according to this breakdown, and the breakdown of these wheels (which are not my due date—my due date is Dec. 4), I will be entering my third trimester on August 21st. That’s 2 weeks 4 days from now. Which is just, well, madness.

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  1. Yeah, there is no rhyme or reason to it– every resource says something different about trimesters. I can’t believe you are so far along! So exciting!

  2. Can’t wait to celebrate! XOXO

    • Me, too! Mocktails all around! My friend in WY and I have this joke that I am going to have a things-i-miss party, a hot tub-sushi-martini party, where everyone can take ibuprofen for no reason. Yay!

  3. So crazy all this calculating and wheels and calendar counting. It always cracked me up that your pregnancy test marks 4 weeks of pregnancy per the counting… 10 months makes sense to me with that whole 40 weeks thing. I don’t get the whole gestational age/fetal age thing, which turns my head around (not that I need to know this yet). I am shocked and excited that you’re only 2 weeks away from the third trimester! Where does the time GO? That’s AMAZING! Enjoy the second trimester while you’ve got it, I’ve heard from little birdies that it’s the BEST. (Other than at the end of the 3rd you get to meet baby boy, can’t imagine much better than that…)

    • It’s absolutely dizzying, isn’t it? I think it’s funny that it took me this long to figure it out. It’s partly because the Mayo book doesn’t delineate the trimesters in a super-clear way (they mention it in-text, not in titles) and I had another breakdown written down elsewhere, and I just got them mixed up….so this whole time I’ve had to keep correcting myself. I think after the precision of the world of ART, it’s hard to accept that things can be so loosey-goosey. XO

  4. I cannot tell you how incredibly helpful this is! Thank you :-)


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