The Ballard Score, or New Ballard Score (NBS), is a bedside assessment tool used to estimate a newborn’s gestational age based on neuromuscular and physical maturity.
It was originally described as the Ballard Maturational Assessment and later revised as the New Ballard Score to extend accuracy down to about 20 weeks’ gestation, including extremely preterm infants.
What does the New Ballard Score measure?
The NBS looks at 12 signs:
- 6 neuromuscular criteria
- Posture
- Square window (wrist)
- Arm recoil
- Popliteal angle
- Scarf sign
- Heel-to-ear
- 6 physical criteria
- Skin
- Lanugo
- Plantar creases
- Breast tissue
- Eye/ear
- Genitalia (male or female)
Each item is scored from −1 to 5 (some physical items can be −2 in certain charts), and the neuromuscular and physical scores are added to give a total score from −10 to 50. Lower scores indicate more immature/preterm infants; higher scores indicate more mature/post-term babies.
New Ballard Score – Gestational Age Estimator
Estimates newborn gestational age from the New Ballard Score (neuromuscular + physical maturity)
For use by health professionals only. This tool converts a completed New Ballard Score into an estimated gestational age. Accuracy is typically within ±2 weeks and is reduced in growth restriction, severe illness, and extreme gestations. Always interpret alongside antenatal dating and clinical context.
Enter New Ballard Score
Total New Ballard Score: –
Estimated gestational age: – weeks (–)
Maturity category: Not yet calculated
Enter the total New Ballard Score (or neuromuscular and physical subtotals), then click “Calculate gestational age” to see the estimated GA and maturity category.
Conversion formula: GA (weeks) ≈ (2 × total Ballard score + 120) / 5, corresponding to a range of ~20–44 weeks for scores −10 to 50. The New Ballard Score is generally accurate to within about ±2 weeks compared with good antenatal dating, but may overestimate GA in preterm and underestimate in growth-restricted infants.
