Pregnancy in Trimesters, Months, and Weeks

By Amanda Doyle
Reviewed by Alyssa Quimby, M.D.
April 23, 2024

Pregnancy is divided into three trimesters. You may hear or read pregnancy information that refers to your pregnancy in terms of the trimester you’re in, but also in terms of the month or week.

It’s important to know what trimester and week of pregnancy you’re in when it comes to the timing of your prenatal care visits and certain tests and screenings.

  • The first trimester, or early pregnancy, includes months 1 to 3, which is weeks 1 to 13
  • The second trimester, or midpregnancy, includes months 4 to 6, which is weeks 14 to 27
  • The third trimester, or late pregnancy, includes months 7 to 9, which is weeks 28 to 40

You may also hear about the fourth trimester. This is not a true stage of pregnancy, but is a name for the first three months of the postpartum period, which is the time after you’ve given birth. These three months (or 12 weeks) are often referred to as another trimester because your body is still adjusting and recovering from pregnancy.