The third trimester of pregnancy usually starts at around 28 weeks and lasts until birth, typically around 40 weeks of pregnancy.

Quick Scoop: Third Trimester Basics

  • Most medical sources define the third trimester as weeks 28–40 of pregnancy.
  • In months, that’s roughly month 7 through month 9 of pregnancy.
  • It ends whenever you actually give birth, which for many pregnancies is around week 39–40, though some go a bit earlier or later.

So if you’re past 28 weeks, you’re generally considered to be in your third trimester.

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The third trimester of pregnancy usually runs from week 28 until birth (around week 40), covering roughly months 7–9, when your baby grows rapidly and your body prepares for labor.

Information gathered from public forums or data available on the internet and portrayed here.