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Clinical calculators and reference tools for Maternal–Fetal Medicine

fullPIERS Risk Prediction Model

Estimates the probability of adverse maternal outcomes within 48 hours for women admitted with pre-eclampsia, using the published fullPIERS equation. This tool is intended for bedside risk stratification in the appropriate clinical setting and should be interpreted together with the overall maternal and fetal picture.

Prediction window48 hours after assessment / eligibility
Core inputsGA, symptoms, SpO2, platelets, creatinine, AST
Published performanceOriginal AUC about 0.88 in derivation cohort
Typical rule-in threshold≥ 30% often used to identify very high risk

Quick clinical notes

  • Use in women with pre-eclampsia being evaluated or admitted.
  • If the patient has de novo postpartum pre-eclampsia, use gestational age at delivery.
  • The original calculator source uses SpO2 = 97% if oxygen saturation is unknown.
  • The model estimates risk; it does not replace clinical judgment, surveillance, or delivery decision-making.
Suggested interpretation: a result ≥ 30% supports a very high-risk profile and has been reported as a useful rule-in threshold in validation work.

Calculator inputs

Enter values from the clinical assessment closest to eligibility / admission.

%
Leave blank to use 97%.
×10⁹/L
µmol/L
U/L
For platelets, ×10⁹/L and ×10³/µL are numerically equivalent.

Results

Predicted probability of adverse maternal outcome within 48 hours
—
Enter inputs and select Calculate risk.
Risk category—
SpO2 used—
Creatinine used—
Gestational age used—
Calculation details
Published logistic equation output:
—
What counts as an adverse outcome?

The fullPIERS model predicts a composite of severe maternal adverse outcomes within 48 hours of assessment.

  • Neurologic: eclampsia, stroke, cortical blindness
  • Respiratory: pulmonary edema
  • Cardiovascular: myocardial ischemia or infarction
  • Hematologic / hepatic: HELLP syndrome, platelets < 50 × 109/L, severe hepatic dysfunction including hematoma or rupture
  • Renal: acute kidney injury requiring dialysis
  • Critical care / organ support: intubation or mechanical ventilation, ICU admission
  • Mortality: maternal death
Clinical interpretation guide
  • < 10%: lower modeled near-term risk, but ongoing maternal/fetal assessment still matters.
  • 10% to < 30%: intermediate modeled risk; reassess with the evolving clinical picture.
  • ≥ 30%: very high modeled risk; validation studies suggest this threshold is useful for ruling in serious maternal complications.

About the model

fullPIERS (Pre-eclampsia Integrated Estimate of Risk) was developed to predict adverse maternal outcomes in women with pre-eclampsia. The original model uses gestational age at eligibility, chest pain/dyspnoea, oxygen saturation, platelet count, serum creatinine, AST, and interaction terms to estimate the probability of serious maternal complications within 48 hours.

Detailed references
  • von Dadelszen P, Payne B, Li J, et al. Prediction of adverse maternal outcomes in pre-eclampsia: development and validation of the fullPIERS model. Lancet. 2011;377(9761):219-227. doi: 10.1016/S0140-6736(10)61351-7. Model equation and derivation performance; original fullPIERS paper. citeturn5search5
  • Ukah UV, Payne B, Karjalainen H, et al. Assessment of the fullPIERS Risk Prediction Model in Women With Early-Onset Preeclampsia. Hypertension. 2018;71(4):659-665. PMID: 29440330. Early-onset preeclampsia assessment of fullPIERS performance. citeturn6search1
  • Ukah UV, Payne B, Karjalainen H, et al. Temporal and external validation of the fullPIERS model for the prediction of adverse maternal outcomes in women with pre-eclampsia. Pregnancy Hypertension. 2019;15:42-50. doi: 10.1016/j.preghy.2018.01.004. External and temporal validation with discussion of ≥30% threshold as a useful rule-in level. citeturn1search6turn6search8
  • UBC PRE-EMPT fullPIERS calculator page. Notes that if SpO2 is unknown, 97% may be used, and that gestational age at delivery is used for de novo postpartum pre-eclampsia. citeturn3view0
Important limitations
  • This calculator supports risk estimation; it does not replace clinician assessment, blood pressure trends, symptoms, fetal status, or delivery planning.
  • The original equation uses AST. If ALT is substituted instead of AST, the estimate is not strictly the published model.
  • Model performance can vary by population and setting; recalibration has been discussed in later validation work.