When do you actually reach the second trimester?? Confused

[SLeeann]

im 11 weeks 3 days and some people say you reach the second trimester at 12 weeks, others say 13 weeks, and even 14 weeks. Im just confused and want to know when i will be in the second tri. all the books i have say different things. its crazy. i dont see my doc again untill 14 weeks so otherwise i would ask him. thanks

[Tarobinc]

Week 13 is the start of the second trimester officially.  But really, Im with cheesecake, close enough is good enough!  

Im just into my 10th week (10.1 days) but I say Im 11wks when asked by people how far along I am.  But techinically Im not quite 11wks because its just the start of my 11wk and I would be 11 wks by this Sunday.  Confused?  Sometimes I cant even keep it straight!

[nikko*ttc]

I have always counted the second trimester from week 13, but some one of my preggo books says week 14 and the other says week 13.

[Cheesecake7]

Well, it is a little conflicting because you cant divide 40 weeks by 3 evenly.

This is my theory:

First Trimester: 1-12

Second Trimester: 13-26

Third Trimester:  27-40

So by my system, which I got from some ladies on the 21-34 pregnancy forum, you reach the second trimester at the end of week 12.  But, I am 12 weeks 5 days, and I am calling it Second Trimester, close enough!!!!

You are almost there no matter how you count it, congratulations Momma!!!!