Pre-eclampsia Risk Calculator

The ASPRE (Aspirin for Evidence-Based Preeclampsia Prevention) trial, published in NEJM in 2017, randomised high-risk women identified by FMF first-trimester screening to aspirin 150 mg nightly or placebo from 11-14 weeks. Aspirin reduced preterm pre-eclampsia (<37 weeks) by 62% in the high-risk group. This landmark trial established first-trimester screening-guided aspirin as the standard of care in many countries.

The evidence-based dose is 150 mg (or 100-162 mg where 150 mg is unavailable) taken at night (bedtime). Night-time dosing exploits the nocturnal peak in thromboxane production and maximises trophoblast invasion during the night. Aspirin should be started before 16 weeks (ideally 11-14 weeks) and continued until 36 weeks gestation.

Placental growth factor (PlGF) is a member of the VEGF family produced by trophoblast cells and is essential for normal placentation. In women who will develop pre-eclampsia, inadequate trophoblast invasion leads to placental ischaemia, which reduces PlGF secretion and stimulates excess production of sFlt-1 (a decoy receptor that sequesters PlGF and VEGF). Low PlGF in the first trimester reflects early impaired placentation.

The sFlt-1/PlGF ratio is used to confirm or rule out pre-eclampsia in women who present with suspected PE (hypertension, proteinuria, or symptoms) after 20 weeks. A ratio <38 rules out pre-eclampsia requiring delivery in the next week with high sensitivity. A ratio >85 (or >110 before 34 weeks in some thresholds) confirms significant disease requiring escalated management.

No. Aspirin is highly effective for preventing preterm pre-eclampsia (<37 weeks) in the identified high-risk group (62% relative risk reduction). Its effect on term pre-eclampsia is much smaller. It does not eliminate risk entirely — women on prophylactic aspirin still require blood pressure monitoring and proteinuria testing at every antenatal visit.

FMF combined first-trimester PE screening with biomarkers is recommended for all pregnant women at 11-13+6 weeks. This is the approach taken in the UK, many European countries, and increasingly internationally. In contrast, NICE UK currently recommends risk factor-based assessment rather than biomarker-based screening, though this is under active review. This is particularly important in the context of preeclampsia risk calculations, where accuracy directly impacts decision-making. Professionals across multiple industries rely on precise preeclampsia risk computations to validate assumptions, optimize processes, and ensure compliance with applicable standards. Understanding the underlying methodology helps users interpret results correctly and identify when additional analysis may be warranted.

High-risk factors (any one triggers aspirin in NICE guidelines): previous PE, chronic hypertension, diabetes, kidney disease, autoimmune disease (SLE, antiphospholipid syndrome). Moderate-risk factors (two or more needed): first pregnancy, age ≥40, BMI ≥35, family history of PE, multi-fetal pregnancy, inter-pregnancy interval >10 years. This is particularly important in the context of preeclampsia risk calculations, where accuracy directly impacts decision-making. Professionals across multiple industries rely on precise preeclampsia risk computations to validate assumptions, optimize processes, and ensure compliance with applicable standards. Understanding the underlying methodology helps users interpret results correctly and identify when additional analysis may be warranted.

Mild pre-eclampsia with well-controlled BP, no severe features, and an sFlt-1/PlGF ratio below 38 may be managed on an outpatient basis with close monitoring (twice-weekly BP checks, weekly blood tests, fetal growth surveillance). Severe features (systolic BP ≥160, platelet count <100, creatinine >97, severe symptoms) require admission and often delivery.