Your pregnancy is divided into three phases, also called the three trimesters: the first trimester, second trimester, and third trimester. Each trimester is 13 or 14 weeks long and together they add up to a total of 40 weeks for your pregnancy. The first trimester lasts until you’re 13 weeks pregnant, the second trimester is from week 14 until week 27, and the third trimester is from week 28 until week 40.
