My opinion they are, I even showed 2 doctors the charts and both laughed at me saying the charts are inaccurate that u go by the weeks 4-12 first trimester 13-28 second trimester 29-42 is 3rd trimester (I may have that wrong not good w math but u get what I mean) there are so many arguments over it but I really don't think it would or should change all of a sudden. It's hard convincing the ftm that it's wrong more than the 2nd 3rd+ times mom would, because we already know what's right and what's wrong.. I hope I'm not confusing u lol @kendallorkaden