A fetal biophysical profile is a prenatal test used to check on a baby's well-being. The test combines fetal heart rate monitoring (nonstress test) and fetal ultrasound to evaluate a baby's heart rate, breathing, movements, muscle tone and amniotic fluid level. The nonstress test and ultrasound measurements are then each given a score based on whether certain criteria are met.
Typically, a biophysical profile is recommended for women at increased risk of problems that could lead to complications or pregnancy loss. The test is usually done after week 32 of pregnancy, but can be done when your pregnancy is far enough along for delivery to be considered — usually after week 24. A low score on a biophysical profile might indicate that you and your baby need further testing. In some cases, early or immediate delivery might be recommended.
A biophysical profile is a noninvasive test that doesn't pose any physical risks to you or your baby. However, it's not always clear that the test improves pregnancy outcomes. Find out what a biophysical profile involves and whether this prenatal test might benefit your baby.
A biophysical profile is used to evaluate and monitor a baby's health. The goal of a biophysical profile is to prevent pregnancy loss and detect a low oxygen supply in the baby (fetal hypoxia) early enough so that the baby can be delivered and not sustain permanent damage.
The test is most commonly done when there's an increased risk of problems that could lead to complications or pregnancy loss. Your health care provider will determine the necessity and timing of a biophysical profile based on whether your baby could survive if delivered early, the severity of your condition and the risk of pregnancy loss.
Your health care provider might initially recommend a modified biophysical profile — a simplified version of the test that includes a nonstress test and assesses amniotic fluid through ultrasound. He or she will use the results to determine whether you need a full biophysical profile, which also measures a baby's breathing, movements and muscle tone, or other tests.
Your health care provider might recommend a biophysical profile if:
- You have a multiple pregnancy with certain complications
- You have a medical condition, such as diabetes, high blood pressure, lupus or heart disease
- Your pregnancy has extended two weeks past your due date (postterm pregnancy)
- You have a history of pregnancy loss or previous pregnancy complications
- Your baby has decreased fetal movements or possible fetal growth problems
- You have too much amniotic fluid (polyhydramnios) or a low amniotic fluid volume (oligohydramnios)
- You have rhesus (Rh) sensitization — a potentially serious condition that can occur when your blood group is Rh negative and your baby's blood group is Rh positive
- You are older than age 35
- You are obese
Your health care provider might also recommend a biophysical profile if you're between 40 and 42 weeks pregnant. The benefits of having the test done during this period, however, aren't clear.
Your health care provider might recommend that you have a biophysical profile once a week or twice a week, depending on your health condition — until you deliver.
A biophysical profile is a noninvasive test that poses no physical risks to you or your baby.
While a biophysical profile can offer reassurance about your baby's health, it can also cause anxiety. In addition, a biophysical profile might not detect an existing problem or might suggest that a problem exists when there is none. A test that falsely indicates a problem might cause your health care provider to recommend unnecessary tests or early delivery.
Also, keep in mind that it's not always clear that the test can improve pregnancy outcomes.
A biophysical profile typically requires no special preparation.
A biophysical profile can be done in your health care provider's office or in a hospital. The test might take 30 minutes or so to complete. A modified biophysical profile takes less time.
During the procedure
During the nonstress test, you'll lie on an exam table and have a belt placed across your abdomen. The belt contains a sensor that measures the fetal heart rate. The heart rate is recorded by a machine. If your baby is asleep, you might need to wait until he or she awakens to ensure accurate results. In some cases, your health care provider might try to awaken the baby by projecting a sound over your abdomen.
During the ultrasound exam, you'll also lie on an exam table. Your health care provider or an ultrasound technician will apply a small amount of gel to your abdomen. Then he or she will roll a small device called a transducer over your skin. The transducer will emit pulses of sound waves that will be translated into a pattern of light and dark areas — creating an image of your baby on a monitor.
Your health care provider or the ultrasound technician will then evaluate your baby's breathing movements, body movements, muscle tone and amniotic fluid level. If your baby is asleep, this portion of the test might take a little longer.
After the procedure
When the biophysical profile is complete, your health care provider will likely discuss the results with you right away.
Each area that's evaluated during a biophysical profile is given a score of 0 or 2 points, depending on whether specific criteria were met. A score can be given immediately. For example:
- Fetal heart rate monitoring. Results of this portion of the test (nonstress test) are interpreted as reactive or nonreactive. If your baby's heartbeat accelerates twice or more a certain amount within a 20-minute period, the results are considered reactive and 2 points will be given. If not enough accelerations occur within a 40-minute period, the results are considered nonreactive and 0 points will be given. Keep in mind that nonreactive results might occur because your baby was asleep during the test.
- Fetal breathing. If your baby displays at least one episode of rhythmic breathing for 30 seconds or more within 30 minutes, 2 points will be given. If your baby's breathing doesn't meet the criteria, 0 points will be given.
- Fetal movement. If your baby moves his or her body or limbs three times or more within 30 minutes, 2 points will be given. If your baby's movements don't meet the criteria, 0 points will be given.
- Fetal muscle tone. If your baby moves a limb from a bent position to an extended position and quickly back to a bent position, 2 points will be given. If your baby's muscle tone doesn't meet the criteria, 0 points will be given.
- Amniotic fluid level. The ultrasound technician will look for the largest visible pocket of amniotic fluid. To obtain a score of 2 points, the pocket must be a certain size. If your amniotic fluid level doesn't meet the criteria, 0 points will be given.
The individual scores are then added together for a total score. Typically, a score of 8 to 10 is reassuring. If you receive a score of 6, your health care provider will likely repeat the test within 24 hours or, if your pregnancy is near term, delivery might be recommended. A score of 4 or lower means that further testing is needed or that you might need to deliver the baby early or immediately.
In addition, if your health care provider finds that you have a low amount of amniotic fluid, you'll need further testing and might need to deliver your baby early — regardless of your overall score.
Certain factors can affect the results of a biophysical profile, including the recent use of corticosteroids to speed your baby's lung maturity. Taking certain medications, such as morphine, also can affect the score.
Be sure to discuss the results of your biophysical profile with your health care provider to fully understand what they might mean for you and your baby.