Understanding Biophysical Profile (BPP): Ultrasound and Nonstress Test in Pregnancy

Comprehensive guide to the Biophysical Profile (BPP), including ultrasound and nonstress test evaluations for monitoring fetal well-being during pregnancy.

By Medha deb

Created on Oct 3, 2025

Biophysical Profile (BPP): Ultrasound and Nonstress Test in Pregnancy

The biophysical profile (BPP) is a vital assessment tool used in the third trimester of pregnancy to evaluate the health and well-being of a developing fetus. Combining ultrasound imaging with a nonstress test (NST), the BPP offers a comprehensive look at fetal health, helping healthcare providers make informed decisions about ongoing pregnancy management.

What is a Biophysical Profile (BPP)?

The biophysical profile is a combination of two diagnostic assessments:

Nonstress Test (NST): Measures the fetal heart rate in relation to fetal movements, assessing how well the baby’s heart responds to its own activity.
Ultrasound Evaluation: Observes various aspects of fetal physiology, including movements, breathing, muscle tone, and amniotic fluid volume, to determine fetal well-being.

By integrating results from both tests, the BPP provides an overall score that reflects the fetus’s current status and oxygenation, helping to detect potential problems before birth.

Why is a Biophysical Profile Done?

The BPP is usually performed in the third trimester of pregnancy, particularly when there are concerns about the baby’s health or in high-risk pregnancies. Common indications for a BPP include:

Abnormal results from other prenatal tests
Mothers with pre-existing health conditions (e.g., hypertension, diabetes, autoimmune disorders)
Suspected fetal growth restriction (baby not growing as expected)
Decreased fetal movement reported by the mother
Pregnancies beyond the due date
Multiple gestations (twins, triplets, etc.)
History of pregnancy loss or complications

The test can reassure parents and caregivers about fetal well-being and, when necessary, guide clinical interventions to prevent complications.

Components of the Biophysical Profile

The BPP evaluates five key fetal activities and conditions:

Fetal Breathing Movements: Movements of the fetal chest or abdominal wall in a breathing-like pattern.
Fetal Body Movements: Gross body movements, such as kicks or limb stretches.
Fetal Muscle Tone: Flexion and extension of limbs or trunk, indicating normal central nervous system function.
Amniotic Fluid Volume: Amount of fluid surrounding the fetus, which reflects kidney and placental function as well as fetal well-being.
Fetal Heart Rate Reactivity (Nonstress Test): Measures changes in fetal heart rate with movement, indicating adequate oxygenation.

Each component receives a score, and the overall total helps providers assess fetal well-being.

Table: Components and Scoring of the Biophysical Profile

Component	Description	Normal (2 points)	Abnormal (0 points)
Fetal Breathing Movements	Observed on ultrasound as breathing-like chest/abdominal movements	At least 1 bout lasting ≥30 secs in 30 minutes	Absent or <30 secs in 30 minutes
Fetal Body Movements	Large limb/trunk movements	At least 3 movements in 30 minutes	Less than 3 movements
Fetal Muscle Tone	Flexion and extension observed	At least 1 episode of extension and return to flexion	Slow extension with partial flexion or absent movement
Amniotic Fluid Volume	Measurement of one or more pockets of amniotic fluid	At least 1 pocket of ≥2 cm in two perpendicular planes	Largest pocket <2 cm
Nonstress Test (NST)	Fetal heart rate reactivity to movement	2 or more accelerations within 20 minutes	Fewer than 2 accelerations or absent reactivity

Preparation for a Biophysical Profile

There are no special preparations required for a BPP. Patients are generally advised to:

Wear comfortable, loose-fitting clothing to the appointment
Eat a light meal beforehand, unless otherwise instructed, as fasting can sometimes influence test results—especially fetal breathing movements
Allow enough time, as the procedure may last up to 60 minutes

It is helpful for patients to have a support person with them if possible, especially if this is their first time undergoing fetal assessments.

How is the Biophysical Profile Performed?

The BPP is an outpatient, noninvasive, and painless procedure. It typically comprises two steps:

Step 1: Nonstress Test
- You will lie on an exam table, and two elastic belts with sensors are placed around your abdomen.
- One sensor monitors fetal heart rate, and the other detects uterine contractions.
- The NST session usually lasts between 20 and 40 minutes, or until adequate data (accelerations) is collected.
Step 2: Ultrasound Evaluation
- A clear gel is applied to your abdomen and a handheld transducer is moved over the skin.
- Over a 30-minute period, the sonographer observes and records fetal breathing, movement, tone, and amniotic fluid.
- If the baby’s sleep cycle prevents observation of certain behaviors, observation continues up to 30 minutes to provide the fetus time to exhibit normal activity.

Scoring and Interpretation of Results

Each component of the BPP receives a score of either 2 (normal) or 0 (abnormal), for a total possible score ranging between 0 and 10. Here is how the results are generally interpreted:

8-10: Normal, reassuring—fetal oxygenation and central nervous system function are adequate.
6: Equivocal or borderline—may require repeat testing within 24 hours or further assessment.
4 or less: Abnormal—suggestive of possible fetal distress or hypoxia, requiring additional investigations or potential intervention.

Clinical decisions following BPP depend on the total score, gestational age, and the mother’s health status. A very low score may prompt early delivery if the risks of remaining in utero are deemed higher than those associated with birth.

What is a Modified Biophysical Profile?

The modified BPP is an abbreviated version that combines the NST with a measurement of the amniotic fluid index (AFI). Here, ultrasound assesses the largest pocket of amniotic fluid in each of the four uterine quadrants, which are summed to calculate the AFI. This shorter approach offers a rapid assessment when a full BPP is unnecessary, though if results are nonreassuring, a full BPP or additional tests may be performed.

Benefits and Risks of the Biophysical Profile

Benefits	Risks
Noninvasive and painless No known risks to mother or fetus Enables timely identification of fetal distress or hypoxia Allows proactive management of high-risk pregnancies Can reduce the likelihood of stillbirth by prompting intervention	No physical risks False-positive or equivocal results may cause unnecessary anxiety Repeated testing may be required if results are unclear or if maternal/fetal factors interfere with observations

Limitations of the Biophysical Profile

The test reflects only the point-in-time assessment of fetal well-being and may need to be repeated as situations change.
Maternal medications, fasting, steroid administration, or fetal sleep patterns can affect results.
Additional tests—such as Doppler studies or extended observation—may be necessary if scores are borderline or abnormal.
Clinical interpretation of BPP should always be matched with the overall picture, including maternal history and risk factors.

What Happens After the Test?

Following the BPP:

Your healthcare provider reviews the score and discusses the results with you.
If the score is normal and there are no complicating factors, routine prenatal monitoring continues.
If the score is equivocal or abnormal, you may be asked to undergo repeat testing, additional assessments (e.g., Doppler flow studies), or, in urgent cases, medical intervention up to or including early delivery.

Healthcare teams always balance the risks of early delivery with the need to prevent complications from fetal hypoxia or distress.

Frequently Asked Questions (FAQs)

Q: Is the Biophysical Profile safe for my baby and me?

A: Yes, the BPP is noninvasive and poses no known risks to either the mother or the fetus. Both the NST and ultrasound components are standard prenatal procedures.

Q: Does the Biophysical Profile hurt?

A: No, the BPP is painless. The NST involves sensors on the abdomen, and the ultrasound uses a gel and a probe moved over the skin. Both are comfortable and safe.

Q: Who should get a Biophysical Profile?

A: Most often, the BPP is recommended for women with high-risk pregnancies or when there is a concern about fetal health based on symptoms, medical history, or other test results.

Q: What do I do if my BPP results are abnormal?

A: If results are abnormal, your provider will advise on next steps, which may include additional tests, closer monitoring, or—if necessary—plans for early delivery. An abnormal result does not automatically mean something is wrong, but it signals the need for further assessment.

Q: How often can a Biophysical Profile be repeated?

A: The BPP can be repeated as often as needed—daily or several times weekly—depending on the clinical scenario. Some high-risk pregnancies require ongoing serial BBP evaluations.

Key Takeaways

The Biophysical Profile combines ultrasound and nonstress testing to provide a real-time view of fetal health.
Most commonly used in the third trimester for high-risk or complicated pregnancies.
BPP scoring helps medical providers make informed decisions about ongoing pregnancy management.
It is a noninvasive and safe test, free of physical risks, and has become a critical component of modern prenatal care.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

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