When does 2nd trimester start

rtcampbell · October 2015

I've seen different comments concerning when does the 2nd trimester begin. is it the 12th,13th,or 14th week? Heartburn has subsided as well as severe bloat and energy comes and goes. How is everyone else feeling? I'm at work and exhausted I need a nap but not until my shift ends at 7pm

Jesse835235 · October 2015

There are conflicting answers of when second tri starts and it all depends on the method of calculation. The three ways to calculate trimesters are by development, conception, or gestation. They all give slightly different answers. The development method starts the second tri at 12 weeks. This uses actual developmental stages to divide the trimesters. From LMP to 12 weeks, the embryo develops all the major organs and becomes a fetus. With the gestation method, you take 40 weeks and divide it in three equal stages, so the second tri would begin at 13w3d. The conception method is where you take 38 weeks of development and divide by three to give you three equal trimesters. By doing this, the second tri occurs in your 14th week.

That's the best explanation I've heard as to why we see differences of trimester dates. I say 13 weeks because I want the second tri to come a week earlier, dangit!

seasalt123 · October 2015

I have heard two things:

1) the beginning of Week 13 (so if you are 12 weeks you are on your final week in the first trimester). This seems to be the most common result I find when I google.

2) the beginning of Week 14. This is what the Bump actually lists as the start of the first trimester and I've seen it in several other places.

So I really don't know. I haven't seen this issue tackled head on in an article anywhere and it certainly is confusing. Similarly, the start of the fetal stage is also sometimes put at the 8th week and sometimes the 9th or 10th.

dsmith211 · October 2015

My midwife said it depends on who you talk to. Like in the case of getting my flu shot she said wait till the second tri at 14 weeks. When I mentioned I thought it was at 13 weeks she said it's really subjective. So sometime around 13-14? Lol.

lest12 · October 2015

I feel like 13 weeks is a safe time to say you are in 2nd trimester.

Which means I'm in 2nd trimester tomorrow - holy crap!

LadySamLady · October 2015

@lest12 me too!! Crazy!

lest12 · October 2015

Right, @ladysamlady!? How is this going by so fast?

sarawifenow · October 2015

I've always been told that the 2nd tri starts at 12 weeks. I had my 12 week scan yesterday at 12w2d and I asked the dr to confirm when 2nd tri starts and he said it is at 12 weeks so I am definitely in the 2nd tri.

stiches221 · October 2015

Second tri- 13w 3d
Third tri-26w6d
But most people just go with 13w and 27w

rtcampbell · October 2015

Thanks everyone I'm 12 w 1d I see my OB on Monday

nba7310 · October 2015

My doctor goes with 12 weeks.

doozer1345 · October 2015

My 2nd trimester checkup is (next week! woo hoo!) when I'll be 12w3d... So I guess for me it will be next Tuesday at 12 weeks according to my doctor.

proudparent2b · October 2015

I was trying to figure this out as well, as I was planning to do a prenatal workout video and wasn't sure whether I should try the first or second trimester routine.