Third trimester? 🆘

Brittney

I use Glow (<a href="https://play.google.com/store/apps/details?id=com.glow.android.nurture">Nurture</a>) and The Bump, and last week at 26 weeks, Glow said I was starting my third trimester, and today at 27 weeks, The Bump says third trimester also. I thought it started at 28 weeks? Can someone clear this up for me? 😅