Ballard Score Calculator

The New Ballard Score (NBS) is a validated clinical tool published in 1991 by Ballard et al. to estimate gestational age in newborns from 20 to 44 weeks. It assesses 6 neuromuscular maturity criteria and 6 physical maturity criteria, producing a total score that maps to a gestational age estimate. It expanded on the original Ballard Score to include extremely premature infants.

Each of the 12 criteria is scored on a scale that typically ranges from -1 (or -2) to 4 or 5. The individual scores are summed to produce a total maturity score. This total score is then mapped to a gestational age using the standard Ballard table: for example, a score of 20 corresponds to approximately 32 weeks, and a score of 35 corresponds to approximately 38 weeks.

The New Ballard Score is most accurate when performed within 12–20 hours of birth. It is typically used in the NICU, delivery room, or nursery for preterm and term newborns, especially when the gestational age is uncertain. Performing it too early (before the infant has recovered from birth stress) or too late can reduce accuracy.

The original Ballard Score (1979) assessed gestational age from approximately 26 to 44 weeks. The New Ballard Score (1991) expanded the scoring system to include extremely premature infants as young as 20 weeks gestation by adding lower score values (e.g., -1 and -2) for the least mature findings. This calculator uses the New Ballard Score.

The 6 neuromuscular criteria — Posture, Square Window (Wrist), Arm Recoil, Popliteal Angle, Scarf Sign, and Heel to Ear — assess the degree of muscle tone and joint flexibility. As gestational age increases, muscle tone increases and range of motion decreases. More mature infants show greater flexion and resistance to passive movement.

The 6 physical criteria — Skin, Lanugo, Plantar Surface, Breast, Eye/Ear, and Genitals — assess the structural maturation of visible and palpable organs. More mature infants have thicker, peeling skin, well-developed ear cartilage, prominent areolae with breast buds, and fully developed genitalia with well-descended testes or prominent labia majora.

The New Ballard Score is generally accurate to within ±2 weeks of the true gestational age when performed correctly and within the first 12–20 hours of life. Its accuracy is highest between 26–42 weeks. For extremely premature infants, results should be interpreted alongside clinical data and obstetric history.

The New Ballard Score is designed for newborns from 20 to 44 weeks gestational age. It is used for both preterm and term infants when gestational age is uncertain. However, it is not a replacement for ultrasound-based gestational age assessment done prenatally — it is used postnatally when obstetric dating is unavailable or uncertain.