When does the 2nd trimester start?

[SQ2]

I feel like everyone has a different answer for this. My whole pregnancy so far, I thought that when you reach 13 weeks, you're definitely 2nd trimester material. But I keep reading people calling 2nd trimester at 14 weeks, not 13, and some people even doing it at 12 weeks. Can we put this issue to rest once and for all? It's not really going to change my mind. I'm pretty much set on saying 2nd trimester begins on Tuesday for me when I'm 13 weeks (and I don't think I can control the fact that my parents are itching to tell people and if I make them wait one more week they may lose it...hehe.). I guess I'm just curious why people say 14 weeks or 12 and what people's reasons are. The pregnancy journal I keep includes week 12 in the 1st trimester, but once you reach week 13 you're in the 2nd. But my doctor said when you're 14 weeks that's more accurate since you're not actually pregnant the 1st two weeks of pregnancy. (Anyone confused yet? ) But when you're 14 weeks pregnant, you're actually 1 day away from starting your 15th week, if that makes sense. (i.e. - I'm 28 right now, but I'm working on my 29th year of life. That kind of thing). So really, on Tuesday I'll be 13 weeks, then Wednesday I'll be starting my 14th week.

AHHHHH....so confusing! Regardless, I'm thrilled to be almost done with the 1st trimester. YAY! If anyone else wants to weigh in that'd be great!

[RobynScott]

Hehe - I think we've all been in the same boat. I asked my obgyn - she said technically 13w3d (since that's 1/3 of 40 weeks) and I went with that.

Congrats on being in the second trimester! (sort of )

[BTB]

Can we put this issue to rest once and for all?

Really doubtful.

The whole idea of dividing up pregnancy into trimesters is just for convenience when talking about it and when generalizing ("when you hit the second trimester your morning sickness should lessen or go away"); there's no real medical or biological point to a dividing line. It really doesn't make any difference if you're first trimester at 13 weeks or 14. It's an "issue" that's been around decades already, and I'm not holding my breath for one answer everyone agrees on anytime soon.

[daisysue62]

I called it at 14 weeks with both my pregnancies because I figured that was 13 complete weeks since when you hit 13 weeks you've only completed 12. I don't think it makes a ton of difference, since I felt about the same at 12 weeks as I do at 14 weeks and which trimester I'm in doesn't really matter.

I'd call yourself in the second trimester whenever you feel you've reached it

[Jess71903]

I'd call yourself in the second trimester whenever you feel you've reached it

ITA with this!

My ticker started the 2nd tri at 14 weeks, but I was confused too...12 weeks is 3 months if you assume 4 weeks per month, but if 40 weeks is full term, then 13.3 weeks is 1/3 of that...Anyway, go ahead and say 2nd tri if you want to!

[stevesbabygirl]

I figured it started at 14 weeks and broke it down like this:

1-13 - First trimester
14-27 - Second trimester
28-40 - Third trimester

In some books, I've seen it as late as 15 weeks!

[SQ2]

Thanks for the input, ladies! It's interesting to hear how everyone thinks about it. I think I'm safely going to assume my 2nd tri begins at 13 weeks since that's at 3 months. Especially since I'll be essentially starting the 14th week anyways. Plus, we're telling everyone this week so there's really no turning back now, even if I wanted to.

[pugzy]

SQ2- I've been wondering the same thing. Some of these pregnancy week by week websites are telling me that I've started the 2nd trimester, but I'm only 12 weeks. I'm going to ask my doctor tomorrow what she thinks it is and go with that. DH and I made the decision not to tell people until the 2nd trimester, so I'm hoping she'll agree with the websites and tell me I'm already there, or that I will be at the end of this week when I'll be 13 weeks!