Individualized posterior risk of preeclampsia (PE) by combining prior risk from maternal factors and medical history with biophysical and biochemical markers through Bayes theorem. Risks can be computed from maternal factors alone or in combination with any available biomarkers.
How to respond / Requirements
Performed by trained healthcare professionals with standardized measurement techniques.
Use validated FMF software or equivalent implementation with correct calibration and MoM adjustments.
Biochemical assays must use validated platforms and reagents; laboratories should report MoM values adjusted for maternal covariates.
Required inputs
Mean arterial pressure (MAP), standardized protocol and device.
Uterine artery pulsatility index (UtA-PI) by Doppler.
Serum biomarkers: PLGF (preferred) and optionally PAPP-A. sFlt-1 is used in late third trimester strategies.
Maternal factors: age, BMI, parity, medical history, ethnicity, prior PE, etc.
Laboratory-reported MoMs adjusted for maternal covariates when available.
Gestational age window
11 to 13+6 weeks: primary combined screening and aspirin eligibility decisions.
19 to 25 weeks: risk re-assessment and management stratification.
30 to 35 weeks: combined late screening (MAP, UtA-PI, PLGF, sFlt-1).
35 to 38 weeks: term-PE focused screening (MAP, PLGF, sFlt-1).
Output and interpretation
Continuous risk estimate (e.g., 1 in X) with locally defined high risk cutoffs.
First trimester combined screening (maternal factors + UtA-PI + MAP + PLGF) detects about 90 percent of early-PE and 75 percent of preterm-PE at a 10 percent screen positive rate (SPR).
In White populations, risk cutoffs of 1 in 100 to 1 in 150 typically yield SPR about 10 to 16 percent with detection rate 88 to 94 percent for early-PE and 69 to 81 percent for preterm-PE.
Performance and SPR vary by population prevalence and covariates (e.g., higher baseline risk in Black women implies higher SPR at the same cutoff).
Evidence and validation
Large prospective cohorts with external validation; FMF algorithms widely adopted internationally.
ASPRE trial: in high risk pregnancies, aspirin 150 mg nightly from 11 to 14 up to 36 weeks reduced early-PE by about 90 percent and preterm-PE by about 60 percent; no reduction for term-PE.
Combined screening by maternal factors, UtA-PI, MAP, and PLGF achieves high detection at acceptable SPR in first trimester.
Clinical considerations and limitations
Standardization and calibration: use validated equipment, follow FMF measurement protocols, and audit MoM distributions periodically. Median MoM should be approximately 1.0 for each biomarker.
Local recalibration: adjust for population-specific prevalence, ethnicity distributions, devices, and lab platforms.
Training: do not implement without formal training and protocol adherence.
Aspirin contraindications: allergy to aspirin, active bleeding, or provider-judged risks. Follow local guidelines for dose and timing.
Practical integration
Perform primary combined screening at 11 to 13+6 weeks to identify high risk for preterm-PE and consider aspirin prophylaxis when eligible.
At 19 to 25 weeks, stratify into high, intermediate, and low risk based on risks for PE before 32 and before 36 weeks, plan closer BP and proteinuria surveillance accordingly, and re-assess at 32 and 35 to 37 weeks as needed.
Use late third trimester screening (30 to 35 and 35 to 38 weeks) to identify women at risk of preterm or term PE and to optimize monitoring and delivery planning.
Maintain regular audits of MAP and UtA-PI measurements and MoMs for PAPP-A, PLGF, and sFlt-1. Investigate deviations from expected distributions. Retrain staff or review sample handling and lab software as required.
Disclaimer: This page is an evidence-based summary for clinicians and does not replace local guidelines or clinical judgment. Follow your institution protocols and regulatory requirements.