Pregnancy typically is measured in three trimesters, each with its own milestones, says the University of California San Francisco.
The first trimester spans the first 13 weeks of pregnancy. During this time, your baby’s structure and organs develop. The changes in your body might cause nausea, fatigue, breast tenderness and frequent urination.
The second trimester spans weeks 14 to 26. You may feel your baby’s first movements inside your belly at this time. Many women have decreased nausea, better sleep patterns and an increased energy level during this period.
The third-trimester is from weeks 27 to 40, as a full-term pregnancy is 40 weeks long. During this time, you may develop hemorrhoids, varicose veins and sleep problems. Babies born before 37 weeks are premature, and may have problems with growth and development.