Third Trimester

Pregnancy is a "low glamour" state, and at no time is this more apparent than in the third trimester (weeks 27 through 40). Everyone asks you how you feel, and you feel great, except for (choose one or more from the following list): heartburn, hemorrhoids, constipation, varicose veins, backache, difficulty sleeping, and the urge to urinate every half hour!

Most of these discomforts are the result of your baby's increasing size. But this continued growth is responsible for exciting developments as well. The fetus moves in a regular pattern each day, and many expectant women get to know their babies' characteristic movements. You need never feel alone; you always have your "buddy" with you.

Prenatal visits should become more frequent in the third trimester, increasing from once every four weeks to every other week. During the last month of pregnancy, you should visit your practitioner once a week. The increasing frequency of visits allows your doctor or midwife to monitor you and your baby more closely for some common complications of pregnancy, including pre-eclampsia (covered in Chapter 10), premature labor, and gestational diabetes.

If there are any concerns about fetal growth, your practitioner will probably order an ultrasound test (covered in the next chapter). If the fundal height is less than expected, you may not be as far along as you thought (perhaps you miscalculated the first day of your last period). If there is other evidence that confirms the gestational age (an earlier ultrasound, or previous exams that were consistent with your original due date), there is a possibility that the baby is not growing properly. An ultrasound exam can determine gestational age as well as fetal size, and thereby explain why the baby may be smaller than anticipated.

If the fundal height is greater than expected, there are other reasons why the fetal size might be greater than gestational age would indicate, including multiple pregnancy (twins, triplets or more) and polyhydramnios (excess amniotic fluid). Once again, ultrasound is the test of choice to further evaluate the discrepancy. However, it is important to remember that in most situations in which an ultrasound is ordered to evaluate fundal heights that are less than or greater than gestational age, nothing is wrong. In those cases, the discrepancy probably represents individual variation. After all, not all babies weigh the same when they are born.

As the third trimester progresses, you'll probably feel increasing excitement (and possibly a bit of apprehension) about your impending labor and delivery. The uterus offers gentle reminders in the form of Braxton-Hicks contractions. These are weak uterine contractions that generally become noticeable in the third trimester. They are normal and can be distinguished from labor contractions in a number of ways. First, they are generally very mild, causing a sensation of "tightening," without pain. Second, they do not develop any regular pattern. Third, they do not become progressively more frequent or more painful; they just go away. It's almost as if the uterus is practicing for the labor ahead.