When does the 2nd trimester start?>

[PetiteWonder]

I am curious as I am very confused of when I woudl be in my 2nd trimester...

I see some peoples saying 1 week until 2nd trimester when they are showing 11 weeks on their trackers...

The tracker seems to put people at 14 weeks in their second trimester..

and other people saying 15 weeks is the 2nd trimester

could someone please clarify this for me?  

[chantal21]

I always say 13 weeks as well. It's so confusing!! lol

[frank_noahsmommy]

I also say 13 weeks, I have a lil booklet my Dr gave me with my last pregnancy and It says 2nd trimester starts on your 13 week, 3rd on your 25th week.

[LosingMyMindInGA]

13 weeks

[cutie_pie84]

Yay! Go Petitewonder & Kelli. I'm shortly behind ladies ! 12 wks.

[kellibubba]

OH yay im in my third trimester...

[PetiteWonder]

i saw someones trackera t 14 weeks saying second trimester.. i guess i have 1 more week to go

[cutie_pie84]

I always thought it began at 14 weeks and the 13th week was your last week in your 1st trimester. But either way ill be rejoicing when I'm completely out of the 1st trimester :)

[babycrazy113]

I always go by the beginning of thirteen weeks too!  But I am assuming medhelp must go by the third method because mine didn't turn to the second trimester until I hit 15 weeks on here!

[NicMom]

I've seen the same thing babycrazy is talking about, but my ob says second trimester starts at 13 weeks so I just go off of that. I am as of today in my second trimester.

[babycrazy113]

This might be helpful for you:

The three basic ways to calculate trimesters  
There are basically three ways of dividing up a pregnancy into the three trimesters; they are by:
Development,   Gestation,   Conception. They give different dates for when the second trimester begins and for when the third trimester begins. Your health care provider might prefer to use the Development method, while another Midwife or Doctor may use the Gestation method.
I am sure they do that just to confuse pregnant women.  
by Development:
This uses actual developmental stages to divide up a pregnancy. From LMP to 12 weeks the embryo develops all the major organs and becomes a fetus. From 12 weeks to 27 weeks the fetus continues developing and reaches viability. From 27 weeks on the fetus finishes development and prepares for delivery. Here the second trimester begins at 12w 0d and the third at 27w 0d.
by Gestation:
With this method you take the 40 weeks of gestation and divide by three. Here the second trimester begins at 13w 3d and the third at 26w 6d.
by Conception:
This method is where you take the 38 weeks of post conception development, divide by three, and add two weeks. Here the second trimester begins at 14w 5d and the third at 27w 3d.

[Clysta]

I was always told 13 weeks is when it starts and that's what I went off of. Some debate is if it's at the start of week 13, or when you finish week 13 making you 14 weeks.