SNAPPE-II (Score for Neonatal Acute Physiology with Perinatal Extension II)

Estimates neonatal illness severity and in-hospital mortality risk from nine acute-physiology and perinatal items assessed over the first 12 hours of NICU admission; a population-level risk score, not a diagnosis or a treatment decision for an individual infant, and temperature must be entered in Celsius (never Fahrenheit).

Mean (arterial) blood pressure — lowest in first 12 h (mmHg)

Lowest body temperature — first 12 h (°C, Celsius only)

PaO₂ at worst oxygenation, first 12 h (mmHg)

FiO₂ at that PaO₂ (fraction 0.21–1.00, not a percent)

Lowest serum pH — first 12 h

Multiple seizures (>1 seizure in first 12 h)

Urine output — lowest over first 12 h (mL/kg/h)

Birth weight (grams, e.g. 1500)

Small for gestational age (<3rd percentile)

Apgar score at 5 minutes (integer 0–10)