Why is Glow saying I'm in the 3rd trimester?!

Question

I'm 26 weeks today and Glow is saying I'm in the 3rd trimester... I'm confused.

Answer

Technically 40 weeks divided into 3 equal parts is 13 weeks and 2-3 days.
Some people round down to 13 and 26.  Some round up to 14 and 28.

Let's Glow!