High-Risk Pregnancy and the Biophysical Profile
A biophysical profile may be scheduled for women whose pregnancies are considered high-risk -- they may have hypertension, a previous stillbirth, or other medical condition, or the fetus is in distress.
What is a Biophysical Profile?
The biophysical profile, or BPP, is a test that checks fetal health in high-risk pregnancies. The BPP combines a non-stress test with an ultrasound exam, and it's usually done after the 28th week of pregnancy.
Several decades ago there were only two ways to check the health of the fetus -- by measuring the size of the uterus and listening to the fetal heartbeat.
In the late 1960s and early 1970s, doctors discovered that changes in fetal heart rate could predict certain problems. Electronic fetal heart-rate monitoring is now widely used to evaluate the health of the fetus.
A test called the non-stress test (NST) is commonly performed to evaluate the health of the fetus. The non-stress test involves placement of a fetal monitor on the mother's abdomen and interpretation of the fetal heart rate in response to fetal movements. It generally takes only 20 to 30 minutes and doesn't require hospital admission.
Interpretation of the non-stress test can sometimes be misleading; there is a relatively high rate of false-positive results, which means that the test may come back positive but the fetus is actually well. Oftentimes, the non-stress test is abnormal, even though there are no problems with the baby, and it's difficult to decide what to do next.
The biophysical profile (BPP) decreases the likelihood of false-positive results by combining the non-stress test with an ultrasound exam. The BPP typically takes 30 minutes, and like the non-stress test, can be done on an outpatient basis.
The ultrasound exam checks four different indicators:
- Fetal tone
- Fetal breathing
- Fetal movements
- Amniotic fluid volume
Each of these four parameters, plus the non-stress test, gets a score from 0 to 2. The scores are then added up for a combined maximum of 10. The interpretation of the BPP score depends on the clinical situation. In general, a score of 8 or 10 is considered normal, while a score below 8 usually requires further evaluation or delivery of the baby.
What a Biophysical Profile Shows
|1 or more extensions of arm/leg or trunk with return to flexion; opening and closing of hand||No or slow movements|
Fetal breathing movements
|1 or more lasting at least 30 seconds within a 30-minute interval||None in 30 minutes|
Gross body movements
|3 or more discrete body/limb movements in 30 minutes||Less than 3 in 30 minutes|
Amniotic fluid volume
|At least one pocket of amniotic fluid 2 cm or more||No amniotic fluid pockets|
The indications for both the non-stress test and the BPP are similar, and your doctor will decide which test is appropriate for your situation.
Reasons to Do a Biophysical Profile
- Overdue pregnancy
- Maternal medical conditions, such as high blood pressure, diabetes, and heart or kidney disease
- Multiple gestation (twins, triplets)
- Decreased amniotic fluid (oligohydramnios)
- Small baby (intrauterine growth restriction)
- Placental abnormality
- Previous unexplained fetal death
- Maternal perception of decreased fetal movement
- Premature rupture of fetal membranes
- Other signs of fetal distress