Fetal Biophysical Profile: What It Is, the Score, and When It Is Indicated
Fetal Biophysical Profile: What It Is, How It Is Scored and When the Doctor Requests It
The biophysical profile is one of the most complete fetal well-being tests in the third trimester. Here we explain its 5 parameters, the Manning scoring system and when it is indicated.
Reviewed by diagnostic imaging specialists · GSMED Imaging ColombiaThe fetal biophysical profile (BPP) is an ultrasound study that evaluates the baby's well-being during the third trimester of pregnancy by combining direct ultrasound observation with the recording of the fetal heart rate. It is, in essence, a "physical exam" of the fetus performed through the maternal abdomen.
Developed by Frank Manning in the 1980s, the biophysical profile integrates five parameters that reflect the functioning of the fetal central nervous system: respiratory movements, body movements, muscle tone, amniotic fluid volume and cardiotocography (NST). Each receives a score of 0 or 2, for a maximum of 10 points.
In Colombia, the biophysical profile is frequently requested in high-risk pregnancies, post-term pregnancies, those with intrauterine growth restriction (IUGR), or when there is a perception of decreased fetal movements. Understanding what it evaluates and how it is interpreted helps healthcare professionals and families understand their results.
What is the fetal biophysical profile?
The fetal biophysical profile is a fetal well-being test that combines real-time ultrasound with cardiotocography (fetal heart rate monitoring). Its purpose is to identify fetuses at risk of chronic or acute hypoxia that could benefit from obstetric intervention.
The physiological basis of the BPP is that the biophysical activities of the fetus —respiration, movement, muscle tone and cardiac reactivity— are controlled by different centers of the central nervous system that mature at different times during gestation. Hypoxia first affects the most recently developed centers (NST, respiratory movements) and preserves the primitive centers (muscle tone) for longer. This allows a hierarchical interpretation of the result.
The BPP is usually performed from the 28th week, although in high-risk situations it may be indicated earlier. It is most frequently used between weeks 32 and 41.
All parameters reflect fetal CNS function, not just cardiac function
Standard window; may be extended if the fetus is in a sleep cycle
Each parameter: 2 points if present, 0 if absent in 30 minutes
Evaluates the acute state of the fetus, not just anatomical structures
The 5 parameters of the fetal biophysical profile
During 30 minutes of observation, the sonographer evaluates five fetal activities. Each receives 2 points if it meets the criterion or 0 points if it does not within the observation time. There are no intermediate scores (there is no 1).
1. Fetal respiratory movements (FRM)
Control center: prefrontal cortex / brainstem nucleiMovements of the fetal chest wall that simulate breathing are observed. To obtain the 2 points, at least 1 episode of respiratory movement of 30 seconds or more is required during the 30 minutes of observation.
Criterion for 2 points: ≥1 episode of FRM of ≥30 seconds in 30 minutes.
0 points: Absence of FRM or episodes <30 seconds.
2. Fetal body movements (FBM)
Control center: basal nuclei / motor cortexThese are movements of the limbs, trunk or whole body of the fetus. Swallowing movements and rolls count. For the maximum score, at least 3 discrete movements are required in 30 minutes.
Criterion for 2 points: ≥3 body or limb movements in 30 minutes.
0 points: ≤2 movements in 30 minutes.
3. Fetal tone (FT)
Control center: cerebral cortex (matures from week 28)Reflects the basal muscle tone of the fetus. It is evaluated by observing that the limbs are in active flexion and that the fetus performs at least one episode of extension followed by return to flexion. The opening and closing of the hand also counts.
Criterion for 2 points: ≥1 episode of active extension with return to flexion of limbs or trunk. Hand opening/closing.
0 points: Limbs in extension, no movement or slow/absent return to flexion.
4. Amniotic fluid volume (AFV)
Chronic marker: reflects long-term fetal renal perfusionAmniotic fluid is produced mainly by fetal urine. Its reduction (oligohydramnios) may indicate compromised renal perfusion secondary to chronic hypoxia. It is measured as the maximum vertical pocket (MVP) or the amniotic fluid index (AFI).
Criterion for 2 points: At least one amniotic fluid pocket ≥2 cm in two perpendicular planes (or AFI ≥5 cm).
0 points: Oligohydramnios — pocket <2 cm or AFI <5 cm.
5. Cardiotocography — NST (Non-Stress Test)
Control center: hypothalamus / brainstem (matures at the end of the 2nd trimester)Cardiotocography records the fetal heart rate (FHR) in response to fetal movements. A reactive NST shows at least 2 accelerations of ≥15 beats per minute in amplitude and ≥15 seconds in duration in 20 minutes, associated with fetal movements.
Criterion for 2 points: Reactive NST — ≥2 accelerations of ≥15 bpm × ≥15 seconds in 20 minutes.
0 points: Non-reactive NST — <2 accelerations in 40 minutes.
Manning scoring system: interpretation
The total score of the biophysical profile ranges from 0 to 10 points. The clinical interpretation and obstetric management depend on the score obtained and the gestational age:
| Score | Interpretation | Asphyxia risk | Recommended management |
|---|---|---|---|
| 10/10 or 8/10* | Normal | Very low (<1/1,000) | Repeat as indicated (weekly or biweekly). No immediate intervention. |
| 8/10 (with low AFI) | Suspicious | Low | Evaluate lung maturity and consider delivery if ≥36 weeks. |
| 6/10 | Equivocal / doubtful | Variable (~90/1,000) | Repeat in 4–6 hours. If it persists, consider hospitalization or delivery according to gestational age. |
| 4/10 | Abnormal | High (~91/1,000) | Hospitalization. Delivery at ≥32 weeks. Individualized management in preterm pregnancy. |
| 2/10 or 0/10 | Very abnormal | Very high (~600/1,000) | Immediate termination of pregnancy regardless of gestational age. Emergency cesarean section if there are signs of asphyxia. |
* 8/10 with normal amniotic fluid and a nonreactive NST (fetal sleep cycle) is interpreted as normal in most protocols. The final management is always decided by the treating obstetrician based on the complete clinical context.
🧭 Hierarchy of parameters in hypoxia
Fetal tone is the last parameter to be lost (the most primitive center), while the NST and respiratory movements are the first to disappear in hypoxia (the most recently matured centers). A 6/10 due to absent fetal breathing movements and a nonreactive NST is more concerning than a 6/10 due to absent body movements.
Modified Biophysical Profile
The modified biophysical profile combines only two parameters: the NST (acute marker of fetal well-being) and the amniotic fluid index (AFI) (chronic marker of placental function). It is a simplified and faster version than the full BPP.
✅ Advantages of the modified BPP
- • Faster (15–20 min vs. 30–45 min)
- • High sensitivity for detecting fetal compromise
- • Less interobserver variability
- • Allows weekly or biweekly monitoring
⚠️ When the full BPP is preferred
- • Nonreactive NST without an apparent cause
- • Abnormal AFI with a reactive NST
- • High risk: severe IUGR, severe preeclampsia
- • When the clinical presentation raises diagnostic doubt
Interpretation of the modified BPP: Normal = reactive NST + AFI ≥5 cm. Abnormal = nonreactive NST or AFI <5 cm → perform a full BPP or proceed according to institutional protocol.
Clinical indications for the biophysical profile
The fetal biophysical profile is indicated in high-risk pregnancies where there is concern about fetal well-being. The main indications include:
Small-for-gestational-age fetuses with abnormal Doppler flow require close monitoring of well-being.
The hyperglycemic environment increases the risk of macrosomia, IUGR, and late fetal death.
Placental aging increases the risk of late fetal hypoxia.
Associated placental dysfunction may compromise fetal oxygenation.
Maternal perception of fewer than 10 movements in 2 hours is an urgent indication.
Systemic lupus erythematosus, chronic kidney disease, heart disease, thrombophilia, among others.
Alterations in amniotic fluid volume require a comprehensive assessment of well-being.
Monochorionic twins with fetofetal transfusion syndrome or growth discordance.
Preparation for the fetal biophysical profile
The biophysical profile is an obstetric ultrasound examination that does not require special preparation, but there are some recommendations that can improve the quality of the study:
You can eat normally before the exam. Some centers suggest eating something sweet 30 min before to stimulate fetal activity.
Drink water normally. A full or empty bladder is not required for this study.
Reserve at least 45–60 minutes. If the fetus is in a sleep cycle, the study may extend up to 90 minutes.
If you have previous ultrasounds, NSTs, or Doppler studies, bring them for comparison and follow-up.
💡 Fetal sleep cycle: Fetuses have active and quiet sleep cycles of 20–40 minutes. If the fetus is asleep at the start of the exam, it is normal for it to take time to show activity. The sonographer can use vibroacoustic stimulation to wake the fetus and shorten the exam time.
What does a result of 6/10 or 8/10 mean?
These are the results that generate the most questions. Here we clarify what each one implies:
⚠️ Result 6/10
A score of 6/10 is considered equivocal or doubtful. It is neither a normal nor a definitively abnormal result. What follows depends on:
- → Gestational age (more concerning in preterm)
- → Which parameters are missing (without an NST it is more serious)
- → The maternal-fetal clinical context
- → The amniotic fluid volume
The usual course of action is to repeat the exam in 4–6 hours. If the 6/10 is confirmed, hospitalization or termination of pregnancy may be indicated.
✅ Result 8/10
An 8/10 is generally normal, but two situations must be distinguished:
- ✓8/10 with normal AFI and nonreactive NST: Probably a fetal sleep cycle. It is considered normal in most protocols.
- !8/10 with reduced AFI: Although the acute parameters are normal, oligohydramnios is a chronic marker of compromise. Termination at ≥36 weeks may be indicated.
The clinical context always prevails over the isolated score.
Does your obstetrics service need ultrasound machines for fetal monitoring?
At GSMED Imaging, we distribute ultrasound equipment with full obstetric capability: color Doppler, integrated cardiotocography, and measurement software for BPP
Request a quote →Frequently asked questions about the fetal biophysical profile
The most common questions from patients and professionals.
