High-Risk Pregnancy and the Biophysical Profile

Question:

I am now 34 weeks into a high-risk pregnancy and I have chronic hypertension. My doctor has scheduled a test for me called a "biophysical profile." What is that?

Answer:

The biophysical profile, or BPP, is a test that checks fetal health in high-risk pregnancies. The BPP combines a nonstress 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 by 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 check on the fetus during pregnancy.

A test called the nonstress test is commonly performed to evaluate the health of the fetus before labor. The nonstress 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 nonstress test can sometimes be misleading because of 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 nonstress 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 nonstress test with an ultrasound exam. The BPP takes 20 to 60 minutes, and like the nonstress 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 nonstress 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
	Normal (Score=2)	Abnormal (Score=0)
Nonstress test	Reactive	Nonreactive
Fetal tone	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 nonstress 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