The First Trimester of Pregnancy: Checkups & Tests Health Article

Prenatal Visits in the Third Trimester

During the third trimester you will start seeing your health care provider more frequently. Be sure to tell your doctor about any new developments and your questions or concerns at each visit. It is better to have all your questions answered during your visit than to have to call your doctor in the middle of the night with a question.

During office visits, you provide a urine sample, are weighed, have your blood pressure taken, and are examined by your doctor. During the physical exam, your doctor listens to the fetal heart rate, feels your arms and legs for edema (swelling), and measures your fundal height (the approximate the length of your uterus).

Determining the Baby's Position

In second half of the third trimester, your doctor tries to determine your baby's position. This is done by performing what is called Leopold's maneuvers - feeling the fetus by palpating first the fundus (top) of the uterus in the upper abdomen, then on either side of the uterus, and finally just above the pubic symphysis of the pelvis. Your doctor first tries to identify the head, which can be felt as a hard, round object. Opposite the head will be the buttocks, which will feel large and squishy. Then, your doctor feels for a long and regular spine. The hands and feet are opposite the spine. Ultrasound can help determine the baby's position, if Leopold's maneuvers are not sufficient.

It is important to identify fetuses that are breech (buttocks first) or transverse (sideways) before labor starts because these positions make delivery more complicated. If you know your baby is in a breech or a transverse position and you start labor or break your bag of waters, go to the hospital immediately. For more information on malpresentation, go to The First Trimester of Pregnancy: Complications.

Checking the Cervix

As you approach term, your provider will check your cervix. This provides information about how your body is preparing for birth. In a first pregnancy, it is common for the cervix to thin and soften (efface) before it actually opens (dilates). If you have had children before, it is not uncommon for your cervix to be dilated before softening or thinning occurs. The cervical examination helps determine whether or not you are really in labor if you arrive at the hospital with your cervix dilated less than 4 cm. Your doctor cannot determine from your cervical examination when you will start labor. If your doctor tells you your labor will start within a certain time, he/she is either guessing or is planning to induce labor (start your labor) if you do not start labor during that time. The cervical exam is also important for determining a plan of care if you are one of the 10% of women who do not deliver by their due date. Many doctors induce labor if the cervix is favorable (dilated and effaced) after 40 weeks gestation. If the cervix is unfavorable, your doctor will probably not start your labor and will give your cervix time to "ripen" and become more favorable.

Estimating the Weight of the Fetus

Your provider estimates the weight of the fetus. Conditions that can make estimating fetal weight less accurate include obesity, fibroids, and excess fluid. Ultrasound can be used to determine fetal weight, but it is not much more accurate than clinical estimates.

Large Fetus

Even if your doctor determines that your baby may be larger than normal, he will probably not recommend a cesarean section. Your body and pelvis are prepared for labor, and most women should attempt vaginal delivery. If the fetus is too large, labor generally stalls. Your provider may then decide to deliver your baby by cesarean section.

Some providers choose to induce labor in women they suspect have a large fetus (large for gestational age, or LGA). LGA pregnancies are often induced before the baby can become macrosomic (more than 4000-4500 grams) because of the risk for birth trauma and failure to progress in labor. (Failure to progress in labor occurs because the baby's head is unable to fit through the mother's pelvis.) Inducing labor is probably beneficial if the cervix is favorable. If not, it may be prudent to allow labor to start on its own. This maximizes the chances of a successful delivery.

Small Fetus

If your fetus is smaller than expected (small for gestational age, or SGA), your provider may order an ultrasound. If the fetus is very small at term, your doctor may want to induce your labor. There is usually no indication to speed up delivery if the baby has been consistently small throughout pregnancy. But if the baby has fallen off the growth curve near term, inducing labor may be indicated. At other times your provider may simply follow your progress with additional testing, such as a nonstress test (NST), oxytocin challenge test (OCT), or biophysical profile (BPP). If these tests are not reassuring, your doctor may go ahead and deliver the baby.

Assessment at the End of the Physical

After completing your physical exam, your provider should have answers to the following questions:

• Is there appropriate fetal growth? At 35 weeks, the fundal height may no longer match the gestational age. (During the second trimester, the fundal height (length of your uterus) in centimeters is approximately equal to the age of the fetus in weeks. For example, if your fundal height is 26 cm, the fetus is about 26 weeks old.) This is partially due to the fetus settling into your pelvis, or "lightening." If your fundal height has grown appropriately and your