Depending on your individual circumstances and risk factors, some additional testing may be required for you or your baby. Here are some of the more common ones:
Biophysical profile (BPP). This is an ultrasound test that assesses the well-being of your fetus. It measures the amount of amniotic fluid, the fetal movements, muscle tone, and determines if the fetus is practicing breathing by moving its diaphragm. This may be ordered routinely once per week starting at 32 weeks for women with certain medical problems or complications, and it also may be used intermittently if, for example, the baby is moving less often than normal.
Nonstress test (NST). This test is also used to assess the well-being of your fetus, and is used in a similar way as the Biophysical Profile. In this case, the fetal heart rate is traced for about twenty minutes and then analyzed by the physician. You will be asked to note every time you feel a movement of the baby. The fetal heart rate usually increases (an acceleration) when the baby moves and seeing this is very reassuring. If this happens twice in 20 minutes, we say that the tracing is reactive.
Growth ultrasounds. For some women at increased risk of a very large or a very small baby, we will follow the fetal growth every three to four weeks with an ultrasound. Ultrasound is not a very good way to estimate how big a baby is due to its margin of error (up to 20%), but the trend over time can tell us if there might be a problem. If the growth is small (fetal growth restriction), we may also measure the flow of blood through the umbilical cord to the placenta to check on the health of the placenta (umbilical artery doppler velocimetry).
Amniocentesis. This is a relatively safe procedure where a needle, under ultrasound guidance, is passed through the abdomen into the uterus and some amniotic fluid is collected. This allows us to test many things, including the chromosomes of the fetus if we need to test for something like Down syndrome, for example.
Other lab tests. Some circumstances may arise that require additional lab testing. If, for example, you develop high blood pressure or hypertension, we may check some additional blood work as well as a 24-hour urine collection to look for protein. This is used to test for a serious condition called preeclampsia.
If you are having a lot of itching, particularly without a rash, we will check your liver function and check your fasting bile salts. This is used to check for an important condition called cholestasis of pregnancy.
If you have any preexisting health problems, you may need certain additional tests to see how well-controlled those conditions are. If you are at high-risk for diabetes or already have it, we will check to see how your blood sugar control is doing. If you have had problems with your thyroid, we will check that. If you have high blood pressure, we will do some tests to see if your major organs, like your kidneys, have been affected by it. There are many other conditions that might require individualized testing.