Trimester question...

Ok, this may be a silly question, but when exactly do the trimesters start and end? :o

I just got to 12 weeks today and got all excited because I thought we'd now made it into the 2nd trimester, but now I'm not sure if it trimester 2 starts at 12 weeks after LMP, or 12 weeks after conception. I tried looking it up, but all the websites say different things, or else they don't specify what their "12 weeks" refers to...

So confusing. :redface:

So if anyone knows for sure, I'd love to know when all of the trimesters start and end :)

i think if you divide the 40 weeks of pg into 3 equal parts it's somewhere around 13w2d for second tri. a lot of places i've read have said 14w (as one third of the max term being 42w)

most places i think tend to agree on 13/14 weeks

Everything I read tells me different things! It's confusing hey!! Once I reached 14 weeks i told myself i was in 2nd trimester.... 14weeks to 28 weeks and then 28 weeks to 40 weeks is 3rd trimester.... that's my theory anyway but you'll hear different things ;)

Congrats on 12 weeks hun! ;)

Thanks girls!

I think I'm going to celebrate 2 milestones then, lol. I'll celebrate today because I'm 12 weeks, then I'll celebrate again in 2 weeks when I'm in the 2nd trimester :ROFL: Any excuse yeah? :)

KL - i celebrate every day that we get through! and the ticking over of each individual week is a huge milestone in itself

Exactly girls!! I celebrate every day that our baby is safe and healthy and I just love each week i reach my new milestone!! Each week is so special :grouphug:

Krystie - lol i celebrated at 12 weeks then 14 weeks and i celebrated at 27 weeks and then 28 weeks as i read in two different sources that i was in 3rd tri that week haha

KL, there are three different ways of counting trimesters as BG said.

If you go by baby development, it's 12 weeks for the end of 1st trimester and 27 weeks for the end of 2nd.

Dividing the 38 weeks of post conception or the 40 weeks of pregnancy gives slightly different answers, particularly for the end of 1st trimester.

The 3rd trimester is a bit more consistent at ending around 27 weeks, but I've noticed that many say it doesn't start until 28 weeks... If you ask an OB, they'll say that 28 weeks is one of the milestones in terms of baby survival if bub is premature, and I suspect that's where the confusion sets in.

My FS gave me a handout at my first scan which showed the exact dates of each trimester ending under the three different ways of calculating... perhaps it's also erring on the side of caution because most people wouldn't know the exact date of conception like we do in IVF.

BW