First trimester vs. Second trimester

samknusre1

My first pregnancy at 11 weeks and want to clarify if 2nd trimester begins with 13 week or when 13 week ends and 14 week starts. I have seen conflicting time frames. Thanks for input.

Lalala2326

There are 3 ways to determine it. 12 weeks if you go by developmental, 13 weeks 3 days by gestational, 14 weeks 5 days? (I think that is right on the third one) by conception. Here is a nifty calculator: https://www.baby2see.com/trimester_calculator.html

Pick whatever you feel comfortable with. It really doesn't matter too much what you call it.