Detection and Monitoring of Pre-Eclampsia in Antenatal Care: A Literature Review of Midwifery Practice

Background to Pre-Eclampsia

The National Institute for Health and Care Excellence (NICE, 2019) defines pre-eclampsia as new-onset hypertension after 20 weeks of pregnancy, with a systolic pressure over 140 mmHg or a diastolic pressure over 90 mmHg, together with at least one new condition: proteinuria, other maternal organ dysfunction or uteroplacental dysfunction such as fetal growth restriction. This broader definition recognises that the disease can be serious even without proteinuria, which changes the emphasis of antenatal assessment from urine testing alone to a fuller clinical picture.

The underlying cause is thought to lie in abnormal placental development, which leads to an imbalance between angiogenic and anti-angiogenic factors in the mother’s circulation. Placental growth factor (PlGF) falls, while soluble fms-like tyrosine kinase-1 (sFlt-1) rises, often weeks before the clinical signs of pre-eclampsia appear. This biology underpins both prevention with aspirin, which is thought to act on placental function when started early, and newer blood tests that help to identify women whose symptoms are caused by placental disease.

Women differ markedly in risk. NICE (2019) lists high-risk factors including hypertensive disease in a previous pregnancy, chronic kidney disease, autoimmune disease such as lupus or antiphospholipid syndrome, type 1 or type 2 diabetes and chronic hypertension. Moderate-risk factors include first pregnancy, age 40 or older, a pregnancy interval of more than 10 years, a body mass index of 35 or more at the first visit, a family history of the condition and multi-fetal pregnancy. Identifying these factors at booking is a core midwifery task.

Search Strategy and Methods

Evidence for this example was identified through targeted searches of openly accessible bibliographic records, publisher websites and the reference lists of key reviews. Search terms combined keywords for the condition (“pre-eclampsia”, “preeclampsia”, “hypertension in pregnancy”, “gestational hypertension”) with terms for prevention, detection and care (“aspirin”, “antiplatelet”, “blood pressure monitoring”, “self-monitoring”, “placental growth factor”, “sFlt-1”, “antenatal care”, “midwi*”), joined with the Boolean operators AND and OR. A full narrative review for assessment would run the same strategy in CINAHL, MIDIRS, PubMed/MEDLINE and the Cochrane Library and report the number of records screened in a PRISMA flow diagram.

Sources were eligible if they addressed the prediction, prevention, detection or monitoring of pre-eclampsia in antenatal care and reported clinical or diagnostic outcomes. National guidelines, Cochrane reviews, randomised trials and large diagnostic studies were prioritised. Studies focused solely on intrapartum treatment, such as magnesium sulfate for eclampsia, or on long-term cardiovascular outcomes after pregnancy were excluded, as they fall outside the antenatal focus of this review.

Six sources published between 2016 and 2022 were included: one national guideline, one Cochrane systematic review, three randomised controlled trials and one prospective diagnostic cohort study (Table 1). The quality of each source was appraised using the Critical Appraisal Skills Programme (CASP) checklist appropriate to its design, supplemented by the AGREE II domains for the guideline. Findings on pre-eclampsia were synthesised narratively and grouped into three themes.

Key Findings on Pre-Eclampsia

Three themes were identified: risk assessment and aspirin prophylaxis, blood pressure monitoring and early detection, and placental growth factor-based testing for women with suspected disease. Table 1 summarises the included sources, and Figure 1 presents the pooled effects of antiplatelet agents on maternal and perinatal outcomes.

Author, year	Design	Setting and sample	Key finding
Zeisler et al. (2016)	Prospective multicentre diagnostic study	1,050 women with suspected disease (500 development, 550 validation)	sFlt-1:PlGF ratio ≤38 ruled out disease within one week (NPV 99.3%); PPV of ratio >38 was 36.7%.
Rolnik et al. (2017)	Randomised controlled trial	1,776 women at high risk of preterm pre-eclampsia	Aspirin reduced preterm disease from 4.3% to 1.6% (OR 0.38).
Duley et al. (2019)	Cochrane systematic review	77 trials, 40,249 women	Antiplatelet agents reduced proteinuric disease (RR 0.82), preterm birth and fetal or neonatal death.
Duhig et al. (2019)	Stepped-wedge cluster RCT	1,023 women with suspected disease; 11 UK maternity units	Revealed PlGF testing cut time to diagnosis from 4.1 to 1.9 days and reduced severe maternal outcomes.
NICE (2019)	National clinical guideline	Hypertension in pregnancy, England	Aspirin 75–150 mg from 12 weeks for women at risk; PlGF-based testing; monitoring schedules.
Tucker et al. (2022)	Randomised controlled trial (BUMP 1)	2,441 women at higher risk; 15 maternity units in England	Self-monitoring with telemonitoring did not detect hypertension earlier (mean difference −1.6 days).

Theme 1: Risk Assessment and Aspirin Prophylaxis for Pre-Eclampsia

Prevention begins with identifying risk. NICE (2019) recommends that women with one high-risk factor, or more than one moderate-risk factor, are advised to take aspirin 75 mg to 150 mg daily from 12 weeks of pregnancy until birth. The guideline also notes that in England aspirin for this purpose must be prescribed rather than bought, a practical point that affects whether women actually receive it. Midwives are often the professionals who identify eligibility, explain the reason for treatment and check adherence.

The evidence for antiplatelet agents is substantial. A Cochrane review of 77 trials with 40,249 women found that antiplatelet agents, mainly low-dose aspirin, reduced proteinuric pre-eclampsia (risk ratio 0.82, 95% CI 0.77 to 0.88; 60 trials), with 61 women needing treatment to prevent one case (Duley et al., 2019). They also reduced preterm birth before 37 weeks, fetal or neonatal death, small-for-gestational-age babies and a composite of serious adverse outcomes.

The relative reduction of around 18% is modest, but because the outcome is serious and aspirin is cheap, the absolute benefit is important. Duley et al. (2019) also found a possible small increase in postpartum haemorrhage over 500 mL (risk ratio 1.06, 95% CI 1.00 to 1.12) and an uncertain effect on placental abruption, so aspirin is not without risk. Two large trials that followed more than 5,000 children to 18 months found no clear difference in development.

Targeting may increase the benefit. In a multicentre trial, 1,776 women at high risk of preterm pre-eclampsia were randomised to aspirin or placebo (Rolnik et al., 2017). Among 1,620 women included in the analysis, preterm disease occurred in 1.6% of the aspirin group and 4.3% of the placebo group (odds ratio 0.38, 95% CI 0.20 to 0.74). Adherence was good, with 79.9% of participants taking at least 85% of their tablets, which shows that the benefit depends on women taking aspirin consistently.

Theme 2: Blood Pressure Monitoring and Early Detection

Accurate blood pressure monitoring is the foundation of detection. NICE (2019) advises that women with gestational hypertension that is not severe should have their blood pressure measured once or twice a week until it is 135/85 mmHg or lower, with dipstick testing for proteinuria at the same visits. Women with severe hypertension need measurement every 15 to 30 minutes until it falls below 160/110 mmHg. Women should also be told to seek help immediately if they develop severe headache, visual disturbance, severe pain below the ribs, vomiting or sudden swelling of the face, hands or feet.

Self-monitoring has been proposed as a way to detect hypertension in pregnancy earlier. In the BUMP 1 trial, 2,441 pregnant women at higher risk were recruited from 15 maternity units in England and randomised to self-monitoring with telemonitoring plus usual care or to usual care alone (Tucker et al., 2022). The mean time to first clinic-recorded hypertension was 104.3 days with self-monitoring and 106.2 days with usual care, a non-significant mean difference of −1.6 days (95% CI −8.1 to 4.9).

This finding is important for midwives because it shows that home readings did not replace or speed up clinic-based detection in this population. The trial was large and well conducted, but it tested earlier detection rather than outcomes such as severe disease, and it was carried out in a setting where antenatal care was already frequent. Self-monitoring may still help some women to feel involved in their care or reduce clinic visits, but it should complement rather than replace professional assessment.

Theme 3: Placental Growth Factor-Based Testing

When pre-eclampsia is suspected, clinical signs alone are a poor guide to who will develop the disease. In a prospective multicentre study, Zeisler et al. (2016) derived a cut-off for the sFlt-1:PlGF ratio in 500 women and validated it in 550 women with suspected disease. A ratio of 38 or lower had a negative predictive value of 99.3% (95% CI 97.9 to 99.9) for ruling out the condition within one week, whereas a ratio above 38 had a positive predictive value of only 36.7% for diagnosis within four weeks.

The PARROT trial tested whether revealing PlGF results improved care. In a stepped-wedge cluster-randomised trial in 11 UK maternity units, 1,023 eligible women with suspected disease were assigned to revealed or concealed testing (Duhig et al., 2019). Revealing results reduced the median time to clinical confirmation from 4.1 days to 1.9 days, and severe maternal adverse outcomes fell from 5% to 4% (adjusted odds ratio 0.32, 95% CI 0.11 to 0.96), with no evidence of a difference in perinatal adverse outcomes.

Reflecting this evidence, NICE (2019) recommends PlGF-based testing on one occasion when pre-eclampsia is suspected in women with gestational hypertension. The value of these tests lies mainly in ruling out disease, allowing women with reassuring results to be managed with less intensive monitoring while focusing attention on those at greatest risk. Their modest positive predictive value means that a raised result still needs careful clinical assessment rather than automatic intervention.

Discussion

This review shows that the evidence on pre-eclampsia now supports a structured pathway: identify risk at booking, offer aspirin to women at increased risk, measure blood pressure accurately throughout pregnancy and use PlGF-based testing when the disease is suspected. Each step is supported by different types of evidence, from a large Cochrane review to pragmatic trials and a diagnostic study, and together they form the basis of current NICE recommendations.

There are tensions within this evidence. Aspirin reduces pre-eclampsia only modestly, and the possible small increase in postpartum bleeding means that it should be offered to women who are likely to benefit rather than to everyone. The Rolnik et al. (2017) trial suggests that screening can identify women in whom aspirin is particularly effective, but such screening requires resources that are not available in every service. Midwives need to understand these trade-offs to explain them clearly to women.

The BUMP 1 result challenges the assumption that more monitoring is always better. Self-monitoring did not lead to earlier detection of hypertension in pregnancy, which suggests that the frequency and quality of professional blood pressure monitoring matter more than adding home readings. Accurate technique, correctly sized cuffs, validated devices and clear action thresholds remain central to safe care. Telemonitoring may still have a role in reducing visits or supporting women after diagnosis, but its benefits for detection were not shown.

Biomarker tests offer a different kind of benefit. By ruling out pre-eclampsia with high confidence, they can reduce unnecessary admissions and allow midwives to reassure women more confidently. The PARROT trial showed faster diagnosis and fewer severe maternal outcomes, although the confidence interval for maternal outcomes was wide and the number of events was small. Implementation also depends on laboratory access, staff training and clear pathways for acting on results.

The evidence base has limitations. Several trials were conducted in high-income settings with well-resourced antenatal care, which may limit transferability. Outcomes such as women’s experience and anxiety were rarely reported. This review relied on openly accessible, English-language sources and did not involve independent double screening. Future research should examine how midwives use biomarker results in practice, whether aspirin adherence can be improved and how self-monitoring can be targeted to women who benefit most from pre-eclampsia surveillance.

Implications of Pre-Eclampsia Evidence for Practice

Midwives should assess risk systematically at booking and at each contact, ensure that eligible women are prescribed aspirin from 12 weeks and check that they are taking it. Every appointment should include accurate blood pressure monitoring with a validated device and an appropriately sized cuff, clear advice about warning symptoms and prompt referral when thresholds are crossed. Relational models such as continuity of carer can help midwives to notice changes, support adherence and build the trust that encourages women to report symptoms early.

Women with hypertensive disease often have other risk factors, such as gestational diabetes, and the disease remains an important contributor to maternal mortality, so care plans should be coordinated with obstetric and medical colleagues. Babies born early because of the condition may need neonatal care, and midwives should plan for skin-to-skin contact and early feeding wherever the baby’s condition allows. Postnatal blood pressure should continue to be monitored, as NICE advises daily measurement in the first days after birth for women with gestational hypertension.

Conclusion

This narrative review examined evidence on the detection and monitoring of pre-eclampsia in antenatal care. Aspirin modestly reduces the disease and its complications in women at increased risk, self-monitoring of blood pressure did not lead to earlier detection, and PlGF-based tests can rule out the condition with high confidence and speed up diagnosis.

For midwives, preventing harm from pre-eclampsia depends on careful risk assessment, accurate and regular measurement, clear advice to women and timely use of biomarker testing. Embedding these steps within relational, well-coordinated care offers the best chance of identifying women early and keeping mothers and babies safe.

References

Duhig, K. E., Myers, J., Seed, P. T., Sparkes, J., Lowe, J., Hunter, R. M., Shennan, A. H., Chappell, L. C., & PARROT Trial Group. (2019). Placental growth factor testing to assess women with suspected pre-eclampsia: A multicentre, pragmatic, stepped-wedge cluster-randomised controlled trial. The Lancet, 393(10183), 1807–1818. https://doi.org/10.1016/S0140-6736(18)33212-4

Duley, L., Meher, S., Hunter, K. E., Seidler, A. L., & Askie, L. M. (2019). Antiplatelet agents for preventing pre-eclampsia and its complications. Cochrane Database of Systematic Reviews, (10), CD004659. https://doi.org/10.1002/14651858.CD004659.pub3

National Institute for Health and Care Excellence. (2019). Hypertension in pregnancy: Diagnosis and management (NICE guideline NG133). https://www.nice.org.uk/guidance/ng133

Rolnik, D. L., Wright, D., Poon, L. C., O’Gorman, N., Syngelaki, A., de Paco Matallana, C., Akolekar, R., Cicero, S., Janga, D., Singh, M., Molina, F. S., Persico, N., Jani, J. C., Plasencia, W., Papaioannou, G., Tenenbaum-Gavish, K., Meiri, H., Gizurarson, S., Maclagan, K., & Nicolaides, K. H. (2017). Aspirin versus placebo in pregnancies at high risk for preterm preeclampsia. New England Journal of Medicine, 377(7), 613–622. https://doi.org/10.1056/NEJMoa1704559

Tucker, K. L., Mort, S., Yu, L.-M., Campbell, H., Rivero-Arias, O., Wilson, H., Allen, J., Band, R., Chisholm, A., Crawford, C., Dougall, G., Engonidou, L., Franssen, M., Green, M., Greenfield, S., Hinton, L., Hodgkinson, J., Lavallee, L., Leeson, P., … McManus, R. J. (2022). Effect of self-monitoring of blood pressure on diagnosis of hypertension during higher-risk pregnancy: The BUMP 1 randomized clinical trial. JAMA, 327(17), 1656–1665. https://doi.org/10.1001/jama.2022.4712

Zeisler, H., Llurba, E., Chantraine, F., Vatish, M., Staff, A. C., Sennström, M., Olovsson, M., Brennecke, S. P., Stepan, H., Allegranza, D., Dilba, P., Schoedl, M., Hund, M., & Verlohren, S. (2016). Predictive value of the sFlt-1:PlGF ratio in women with suspected preeclampsia. New England Journal of Medicine, 374(1), 13–22. https://doi.org/10.1056/NEJMoa1414838