Trimesters

Pregnancy trimesters mean that your pregnancy is divided into three phases: the first trimester, second trimester, and third trimester. Each trimester is 13 or 14 weeks long to equal 40 weeks of pregnancy. The first trimester lasts until you're 13 weeks pregnant, the second trimester spans week 14 to week 27, and the third trimester starts the day you turn 28 weeks pregnant and lasts until week 40 – though you're likely to deliver your baby a few weeks before or after that.