When does third trimester start?

Question

I see so many different answers I'm genuinely curious. For my doctor it starts at 28 weeks. When does it start for your doctor's or yourselves?

Answer

Each trimester is technically 13 1/3 weeks long (40/3), so 26 2/3 weeks is end of 2nd trimester. 
My doctor says 14 weeks starts 2nd trimester and 27 weeks starts 3rd trimester.

Answer

At the end of 27 weeks so basically 28 weeks.

Answer

My doc says it’s in your 28th week. Which is 27+1

Answer

I was told like.. 27 1/2 weeks

Answer

My dr said 27wks

When does third trimester start?

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