The Third Trimester (Weeks 28–40)
The final stage of pregnancy, weeks 28 through 40, is often marked by excited expectation of the baby’s arrival. At this stage, it is a good idea to have your hospital overnight bag packed and ready to go.
Development. The growing fetus begins to be aware of its surroundings as the third trimester gets underway. Early in the third trimester, the fetus begins to open and close its eyes and suck its thumb. He or she also begins to respond to light and sound. As the fetus continues to grow, it has less and less room to move around. Some women report being able to identify the shape of an elbow or a heel poking into their abdomen. At the end of this trimester, (and the end of the pregnancy), the fetus moves into the position for birth, which usually means he or she moves into a "head down" position lower in the mother's abdomen, nearer to her pelvis.
The Mother's Experience. The third trimester can be marked by physical discomfort associated with the now large size of the developing baby and mother's associated weight gain. It is common for third trimester mothers to experience heartburn, significant hemorrhoids, increased body temperature, and more fatigue. Additionally, many women experience swelling in their ankles and fingers. Although some swelling is normal, you should alert your physician if you notice sudden, extreme swelling, or if you experience a rapid, sudden weight gain. These two symptoms may indicate a serious condition called pre-eclampsia (previously described in detail) which could harm your baby.
A new experience during this final phase of pregnancy is the onset of Braxton Hicks contractions, which signal that your body is preparing itself for labor. Braxton Hicks contractions occur in the uterus, last about 30 to 60 seconds each, and are usually painless. In contrast to Braxton Hicks contractions, real labor contractions occur with greater intensity, regularity, and frequency. Real labor contractions become more painful over time rather than getting better or less intense with time as will Braxton Hicks contractions.
Complications. The third trimester ends with labor and the birth of the baby. It remains possible to enter into pre-term labor prior to your due date. Contact your physician to make sure you are not in preterm labor if you experience contractions that are accompanied by a watery or bloody discharge or back pain, or if you find you have more than 8 contractions per hour, occurring at regular intervals.