👶 New Ballard Score (Gestational Age)
Estimate neonatal gestational age with the New Ballard Score.
Clinical takeaway
Accuracy ± 2 weeks; most accurate at 12–48 h of life.
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When to use
Assign gestational age when dating is unknown or discordant with the exam.
How it works
GA (weeks) = 24 + 0.4 × total of neuromuscular (6 items) and physical (6 items) maturity subtotals; total −10 to 50 maps to ~ 20–44 weeks.
Key points
- Accuracy ± 2 weeks; most accurate at 12–48 h of life.
- May overestimate in small-for-gestational-age infants.
- Cross-check with prenatal ultrasound/LMP.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Neuromuscular maturity subtotal (6 items: posture, square window, arm recoil, popliteal angle, scarf sign, heel-to-ear) | 12 points |
|---|---|
| Physical maturity subtotal (6 items: skin, lanugo, plantar surface, breast, eye/ear, genitals) | 13 points |
→Estimated gestational age34 weeks
- Total：Neuromuscular 12 + physical 13 = 25 → GA = 24 + 0.4 × 25 = 34 weeks (Late preterm)
- Conversion：GA (weeks) = 24 + 0.4 × total; total −10 to 50 maps to ~ 20–44 weeks; +5 points ≈ +2 weeks
- Accuracy：± 2 weeks; most accurate at 12–48 h of life (< 12 h better for the extremely preterm). May overestimate in small-for-gestational-age infants; cross-check with prenatal ultrasound/LMP
Frequently asked questions
- What is New Ballard Score (Gestational Age)?
- Estimate neonatal gestational age with the New Ballard Score.
- How is New Ballard Score (Gestational Age) calculated? What is the core formula?
- GA (weeks) = 24 + 0.4 × total of neuromuscular (6 items) and physical (6 items) maturity subtotals; total −10 to 50 maps to ~ 20–44 weeks.
- When is New Ballard Score (Gestational Age) used?
- Assign gestational age when dating is unknown or discordant with the exam.
- What are the key clinical points for New Ballard Score (Gestational Age)?
- Accuracy ± 2 weeks; most accurate at 12–48 h of life. May overestimate in small-for-gestational-age infants. Cross-check with prenatal ultrasound/LMP.
- What are the limits and cautions when using New Ballard Score (Gestational Age)?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is New Ballard Score (Gestational Age) calculated in practice? Can you show a worked example?
- Inputs: Neuromuscular maturity subtotal (6 items: posture, square window, arm recoil, popliteal angle, scarf sign, heel-to-ear) 12 points, Physical maturity subtotal (6 items: skin, lanugo, plantar surface, breast, eye/ear, genitals) 13 points → Result: Estimated gestational age 34 weeks（Total: Neuromuscular 12 + physical 13 = 25 → GA = 24 + 0.4 × 25 = 34 weeks (Late preterm), Conversion: GA (weeks) = 24 + 0.4 × total; total −10 to 50 maps to ~ 20–44 weeks; +5 points ≈ +2 weeks, Accuracy: ± 2 weeks; most accurate at 12–48 h of life (< 12 h better for the extremely preterm). May overestimate in small-for-gestational-age infants; cross-check with prenatal ultrasound/LMP）