The biophysical profile (BPP) is a comprehensive ultrasound assessment of fetal wellbeing that scores five different variables. It provides more information than a non-stress test alone and is used when there is concern about how a baby is coping.
The Five BPP Components
| Component | What Is Checked | Score (each) |
|---|---|---|
| Non-stress test (NST) | Heart rate accelerations over 20–40 minutes | 0 or 2 |
| Fetal breathing | At least 1 breathing episode of 30+ seconds in 30 minutes | 0 or 2 |
| Fetal movement | At least 3 discrete body movements in 30 minutes | 0 or 2 |
| Fetal tone | At least 1 extension-flexion movement (limb or spine) | 0 or 2 |
| Amniotic fluid | Single deepest pocket 2+ cm or AFI 5+ cm | 0 or 2 |
What the BPP Score Means
| Score | Interpretation | Management |
|---|---|---|
| 8–10 | Normal — no fetal compromise | Routine care, repeat if indicated |
| 6 | Equivocal — possible compromise | Repeat in 24 hours; consider delivery if at term |
| 4 | Abnormal — possible compromise | Delivery usually recommended |
| 0–2 | Strongly suggestive of compromise | Delivery usually indicated urgently |
Modified BPP
Many centres use a modified BPP — just the NST plus amniotic fluid volume. This takes less time and is used for routine monitoring. A full BPP is done when the modified BPP is abnormal or when more information is needed.
Why BPP Isn't Perfect
A sleeping baby can score low on breathing, movement, and tone despite being completely healthy. The amniotic fluid component is the most reliable because fluid volume reflects kidney function over days — not just the current sleep-wake cycle. An abnormal AFI alongside other low scores is more significant than a low score on the reactive components alone.
Note
The BPP is a screening tool, not a diagnosis. Decisions about delivery are made based on the whole clinical picture — BPP, Doppler, gestational age, and the mother's condition.