Preeclampsia Biomarkers: Predicting Early-Onset Disease

Early-onset preeclampsia is one of the most serious complications of pregnancy. It can develop rapidly, threaten the health of the pregnant person and baby, and require birth weeks before the due date. The condition is usually defined as preeclampsia diagnosed before 34 weeks, although some clinical studies use 37 weeks as the threshold for early disease.

The biological changes often begin before high blood pressure or proteinuria become obvious. Abnormal placental development, impaired maternal blood-vessel adaptation and inflammation can progress silently during the first and second trimesters. This has created strong interest in biomarkers that identify women at increased risk before clinical signs appear.

A biomarker cannot replace blood pressure measurement, urine testing, ultrasound or clinical judgement. Its value lies in adding information: helping clinicians distinguish a low-risk pregnancy from one that needs closer surveillance, specialist referral or timely admission. The most useful tests are those that improve decisions rather than simply produce another number.

The subject sits within the wider scientific conversation represented by the FAOPS 2020 congress site, which documented a major meeting in Tokyo devoted to perinatal and neonatal medicine before the event was cancelled during the COVID-19 pandemic. Research presented across this field continues to influence how pregnancy complications are detected, managed and discussed with families.

What Makes Early-Onset Preeclampsia Different

Preeclampsia involves new-onset hypertension after 20 weeks of pregnancy together with proteinuria or signs of maternal organ dysfunction. These may include reduced platelet levels, abnormal liver function, kidney impairment, pulmonary oedema, neurological symptoms or evidence of placental dysfunction such as fetal growth restriction. Early-onset cases are more frequently associated with placental disease and severe maternal or fetal complications than cases diagnosed near term.

The condition is not a single, uniform disorder. Some pregnancies show clear problems with placental implantation and uteroplacental blood flow, while others involve stronger maternal cardiovascular or metabolic susceptibility. A history of preeclampsia, chronic hypertension, kidney disease, diabetes, autoimmune disease, multiple pregnancy and certain fertility treatments can increase risk, but the absence of these factors does not guarantee safety.

Early delivery is often the definitive treatment because the placenta drives the disease process. Before that point, care may involve frequent blood pressure checks, blood tests, fetal growth scans, umbilical artery Doppler studies, corticosteroids for fetal lung maturation and magnesium sulfate when seizure prevention or fetal neuroprotection is indicated. Better prediction could allow these interventions to be planned more safely.

Why Biomarker Testing Matters Before Symptoms

A screening marker estimates the chance that a condition will develop. A diagnostic marker helps assess whether disease is present now. This distinction is essential. A low biomarker result should not dismiss new symptoms, while a high result does not automatically mean that delivery is required.

One of the strongest clinical applications is triage for women with suspected preterm preeclampsia. A woman may present with rising blood pressure, headache, visual disturbance, upper abdominal pain, swelling or reduced fetal movement, yet have findings that are not initially decisive. Biomarkers can contribute to the assessment of whether she is likely to develop preeclampsia within a defined period.

The sFlt-1/PlGF ratio has been studied particularly extensively in this setting. Soluble fms-like tyrosine kinase-1, or sFlt-1, binds pro-angiogenic factors, while placental growth factor, or PlGF, supports healthy placental blood-vessel development. An elevated ratio generally reflects an anti-angiogenic state associated with placental dysfunction. A low ratio can be reassuring for short-term risk in selected women, but cut-offs and testing intervals depend on the assay, gestational age and local protocols.

The Main Biomarker Families

PlGF is a placental angiogenic marker that tends to be lower in pregnancies affected by placental insufficiency and early preeclampsia. It may assist with risk assessment before overt disease and with triage after symptoms develop. Because concentrations change throughout gestation, interpretation should use gestational-age-specific reference ranges rather than a single universal threshold.

The sFlt-1/PlGF ratio combines a harmful anti-angiogenic signal with a protective placental signal. It has the advantage of reflecting the balance between these pathways instead of relying on one molecule. However, different commercial platforms do not produce interchangeable results. Laboratories must validate their methods, and clinicians need to know which cut-offs apply to the specific test used.

Other candidates include soluble endoglin, pregnancy-associated plasma protein A, placental protein 13, inhibin A and activin A. Uterine artery Doppler resistance, maternal blood pressure and biochemical markers can also be combined in multivariable prediction models. First-trimester screening may incorporate maternal characteristics, mean arterial pressure, uterine artery pulsatility index and PlGF to estimate the likelihood of preterm preeclampsia.

Cell-free RNA, extracellular vesicles, metabolomic signatures and machine-learning models are promising research areas. Their scientific potential is considerable, yet discovery is not the same as clinical readiness. A new test must show reproducible performance across ethnic groups, body-mass categories, gestational ages and healthcare settings before it can support routine decisions.

From Results To Safer Clinical Decisions

The practical value of a biomarker depends on what changes after the result is known. A high-risk result might prompt maternal-fetal medicine review, more frequent blood pressure and blood-test monitoring, additional fetal growth assessment or transfer to a hospital with neonatal intensive care. A reassuring result might help avoid unnecessary admission when the rest of the assessment is stable.

Prediction models should report both sensitivity and specificity, as well as positive and negative predictive values in the population being tested. The consequences of a false negative can be serious, while false positives may cause anxiety, hospital stays, additional procedures and earlier birth. Clinicians therefore need clear pathways that explain how a result fits with symptoms, examination, laboratory findings and ultrasound.

The timing of testing matters. A marker measured at 12 weeks may estimate future placental risk, whereas a test at 30 weeks may help assess short-term deterioration. Results can also change as pregnancy progresses. Serial testing may be useful for selected patients, but repeated blood collection should have a defined clinical purpose rather than becoming routine without evidence.

The best approach combines biomarkers with established preventive and monitoring strategies. For women at increased risk, clinicians may consider low-dose aspirin started early in pregnancy according to Australian and international guidance. Calcium supplementation can be relevant where dietary calcium intake is low. These measures require individual assessment, especially when there are bleeding risks, allergies, medication interactions or complex medical histories.

Australian Access And Clinical Context

Australian care varies considerably between a tertiary maternity service in Melbourne, Sydney or Brisbane and a small hospital serving rural Queensland or the Northern Territory. A patient who lives near a specialist maternal-fetal medicine unit may have rapid access to angiogenic marker testing, advanced ultrasound and neonatal intensive care. Someone in a remote community may need pathology transport, telehealth review and careful planning for travel before deterioration occurs.

The public and private systems also have different pathways for ordering tests, covering costs and arranging follow-up. Availability through hospital laboratories and commercial pathology providers is changing, and an assay may be accessible in one metropolitan service but unavailable in a regional facility. Clinicians should verify local laboratory accreditation, turnaround time, validated reference ranges and funding arrangements before relying on a result.

Australian practice must also account for the needs of Aboriginal and Torres Strait Islander families, who can face substantial barriers linked to distance, transport, housing, continuity of care and culturally unsafe services. A prediction model developed in a European population may not perform identically in Australian communities. Research should include diverse populations and involve Aboriginal health services in study design, interpretation and implementation.

Communication is part of safe biomarker use. Families need to understand that an elevated risk does not mean that preeclampsia is inevitable, and a reassuring result does not remove the need to report symptoms. Culturally safe care, interpreters, written information and shared planning can make a major difference, particularly when a patient may need to relocate from a regional area to a city hospital.

Research Priorities And Family Care

Future studies should test whether biomarker-guided care improves outcomes, rather than stopping at improved prediction statistics. Important outcomes include severe maternal complications, fetal growth, gestational age at birth, neonatal intensive care admission, psychological wellbeing, hospital costs and equity of access. Trials should compare biomarker strategies with existing care and define how clinicians respond to each result.

The neonatal consequences of early delivery extend beyond the pregnancy ward. Babies born after severe placental disease may need respiratory support, feeding assistance, temperature regulation and prolonged monitoring. Perinatal research therefore benefits from a whole-family perspective, including the principles discussed in family-centred NICU care. A test that predicts risk is most valuable when it connects families with appropriate support before and after birth.

The same principle applies when neonatal teams manage other complex conditions. For example, clear clinical pathways and coordinated communication are central to neonatal opioid withdrawal treatment. Biomarker research should aim for similar clarity: defined thresholds, documented actions, respectful counselling and smooth handover between antenatal, maternity and neonatal services.

Patients should also be protected from unnecessary commercial enthusiasm. A test marketed as an “early warning” tool may sound definitive even when evidence is limited to a particular gestational age or clinical population. Independent evaluation, transparent reporting and regular review of local outcomes are needed before widespread adoption.

Clinicians, researchers and maternity services can advance this field by reviewing current preeclampsia pathways, identifying where risk assessment is weakest and supporting well-designed Australian studies. Patients with concerns about blood pressure, headache, visual changes, sudden swelling or reduced fetal movement should seek urgent maternity advice, while healthcare teams should use validated biomarkers as one part of attentive, individualised care.