Pre-eclampsia affects around 6% of pregnancies and is one of the most serious complications in obstetric medicine — yet its early symptoms are easy to dismiss. This guide covers what it is, why it happens, who is at risk, what the warning signs are, what treatment involves, HELLP syndrome, and what life after pre-eclampsia looks like — including the long-term health picture most people are never told about.
🩺 Open full guide in WiseMama — freePre-eclampsia is a pregnancy-specific condition involving new-onset high blood pressure after 20 weeks of pregnancy, combined with damage to other organs — typically the kidneys, liver, and brain. It affects approximately 6% of pregnancies in the UK and is a leading cause of maternal death in high-income countries. With appropriate monitoring and treatment it is usually managed well; without it, it can escalate to life-threatening complications within hours.
Understanding why pre-eclampsia develops explains its behaviour — why it can appear suddenly, why only delivery cures it, and why some pregnancies are at higher risk than others.
Stage 1 — abnormal placentation (first trimester, silent): In early pregnancy, the placenta should deeply embed into the uterine wall and remodel the maternal arteries to create a wide, high-flow blood supply. In pre-eclampsia, this process is incomplete — the arteries remain narrow, leaving the placenta under-perfused. This happens weeks before any symptoms and cannot be detected by the woman herself.
Stage 2 — maternal syndrome (typically second or third trimester): The under-perfused placenta releases vasoactive proteins into the maternal bloodstream that cause widespread damage to the endothelium — the lining of blood vessels. The consequences are vasospasm (causing hypertension), kidney inflammation (causing proteinuria), liver stress (causing the characteristic right-sided pain), and in severe cases, brain effects (causing headache, visual disturbance, and in extreme cases, seizures).
Because the placenta is the source of the disease process, delivery is the only definitive cure. Medication manages the manifestations but does not resolve the underlying problem.
Early-onset pre-eclampsia (before 34 weeks) is less common but more severe — driven predominantly by placental dysfunction with greater maternal and fetal consequences.
Late-onset pre-eclampsia (after 34 weeks) is more common and often milder — though it can still escalate rapidly. Aspirin from early pregnancy primarily reduces early-onset disease.
Pre-eclampsia is not entirely predictable, but several factors are associated with significantly elevated risk. Knowing them matters both for prevention and for ensuring the right level of monitoring.
First pregnancy; age 40 or above; BMI above 35 at booking; family history of pre-eclampsia in mother or sister; inter-pregnancy interval of more than 10 years.
The ASPRE trial (2017) demonstrated that low-dose aspirin (150mg, taken at night, from 11–14 weeks) reduced early-onset pre-eclampsia by approximately 62% in high-risk pregnancies. This single trial transformed prevention practice and is the basis for NICE guidance recommending aspirin for all women with high-risk factors from booking. If you have relevant risk factors and aspirin has not been offered or discussed at your booking appointment, raise it proactively.
The first trimester combined test (at 11–13 weeks) can assess PE risk using blood pressure measurement, uterine artery Doppler, and blood markers including placental growth factor (PlGF). A high-risk result triggers early aspirin and additional monitoring; a low-risk result is genuinely reassuring. This screening is becoming increasingly available at NHS fetal medicine units — ask whether it is offered at your unit if you have risk factors.
The symptoms of pre-eclampsia are individually easy to explain away in pregnancy. The MBRRACE report on maternal deaths consistently identifies delayed recognition of severity as a preventable factor. Understanding which symptoms warrant same-day contact — not a wait-and-see approach — is one of the most important things in this guide.
Severe headache that doesn't resolve with paracetamol. Not a mild tension headache — a persistent, severe headache, often frontal or occipital, that paracetamol doesn't touch. This reflects cerebral vasospasm and rising intracranial pressure.
Visual disturbances. Flashing lights, blurred vision, seeing spots or floaters, or any change in vision. These indicate brain involvement and are a warning sign of impending eclampsia. Any visual disturbance in the second half of pregnancy needs same-day assessment.
Severe pain just below the ribs, particularly on the right side. This is liver involvement — subcapsular liver pain or early haematoma. It is frequently mistaken for heartburn or indigestion. Right-sided subcostal pain in pregnancy that does not respond to antacids always needs assessment.
Sudden significant swelling of the face or hands. Gradual ankle oedema is common in normal pregnancy. Sudden facial or hand swelling, particularly if it comes on rapidly or is asymmetric, is more concerning.
A general sense of being severely unwell. Parents and clinicians both describe this as a distinct clinical signal — a sudden deterioration in how you feel that is different from normal pregnancy discomfort.
You have severe headache with visual disturbance · Severe right-sided or upper abdominal pain · Blood pressure ≥160/110 if you are monitoring at home · Sudden collapse or seizure · Reduced fetal movements alongside any of the above
Do not wait for your next scheduled appointment. Pre-eclampsia can escalate from mild to life-threatening in hours. A normal blood pressure reading at a recent appointment does not protect against rapid deterioration.
If pre-eclampsia is suspected or confirmed, you will be closely monitored — in hospital or at a day assessment unit depending on severity. Understanding what is being checked makes the experience of repeated blood tests more meaningful.
Blood pressure ≥140/90 on two occasions at least four hours apart defines hypertension in pregnancy. Severe hypertension — ≥160/110 — is a medical emergency. Automated machines can be inaccurate in pre-eclampsia; your team may use manual measurement for confirmatory readings. The target with treatment is typically below 150/100 — not complete normalisation, which can compromise placental blood flow.
Dipstick screening, followed by protein-creatinine ratio (PCR) or 24-hour urine collection if dipstick is positive. A PCR ≥30 mg/mmol or 24-hour protein ≥300mg is significant. Proteinuria alone does not determine severity — the full clinical picture does.
Full blood count (platelet count — falling platelets indicate HELLP developing), liver function tests (ALT, AST — rising indicates liver involvement), renal function (creatinine, urea — rising indicates kidney injury), and uric acid (a severity marker). These are repeated every 12–48 hours in hospital depending on the clinical picture.
Placental Growth Factor is a biomarker produced by the placenta that falls significantly in pre-eclampsia before clinical symptoms fully develop. NICE approved PlGF testing in 2022 as a tool to rule pre-eclampsia in or out in women with suspected symptoms. A result below 100 pg/mL indicates high risk of needing delivery within 14 days. Ask whether this test is available at your unit if you present with suspected pre-eclampsia.
CTG (continuous fetal heart rate monitoring), growth ultrasound, and umbilical artery Doppler assessment of placental blood flow. Abnormal Doppler waveforms — particularly absent or reversed end-diastolic flow — indicate severe placental compromise and may trigger delivery decisions.
Treatment aims to control blood pressure to reduce the risk of stroke and organ damage, prevent seizures, and monitor closely while preparing for delivery at the safest possible time. It cannot resolve pre-eclampsia — only delivery does that.
The immediate priority in severe pre-eclampsia is lowering blood pressure below the stroke threshold. First-line options in UK practice:
All are safe in pregnancy. The target is blood pressure below 150/100 — not normalisation, which can impair placental perfusion.
Given intravenously to prevent seizures (eclampsia) in women with severe pre-eclampsia. It is not an antihypertensive — it does not lower blood pressure. It reduces cerebral irritability and is the most effective agent for eclampsia prevention. Side effects — flushing, warmth, nausea — are predictable and monitored closely by nursing staff. Understanding this distinction (antihypertensives for blood pressure; magnesium for seizure prevention) helps make sense of why both are used simultaneously.
Pre-eclampsia causes fluid to leak from blood vessels into tissues — the blood vessels are relatively depleted while tissue oedema accumulates. Aggressive IV fluid replacement risks tipping this balance into pulmonary oedema (fluid in the lungs). Fluid restriction to around 80 mL/hour is standard in severe pre-eclampsia, with careful input/output monitoring.
If delivery is anticipated before 34 weeks, two injections of betamethasone 24 hours apart are given to accelerate fetal lung maturity and significantly reduce the risks associated with preterm delivery.
When they explained that magnesium sulphate would prevent seizures but not bring my blood pressure down — and that the two were completely separate problems being treated at the same time — it was the first time the whole picture made sense to me. Nobody had explained it as a whole before that point.
HELLP syndrome is a severe complication of pre-eclampsia that warrants its own section — because it can develop without the hallmarks of severe hypertension, and because its symptoms can look like something much less serious.
H — Haemolysis: red blood cells are breaking down abnormally.
EL — Elevated Liver enzymes: the liver is under significant stress.
LP — Low Platelets: clotting cells are being depleted, raising the risk of serious bleeding.
HELLP can present without severely elevated blood pressure. The symptoms — right upper quadrant or epigastric pain, nausea, vomiting, malaise, sometimes jaundice — can be attributed to gastroenteritis, gallbladder disease, or late pregnancy discomfort. Diagnosis requires blood tests revealing falling platelets and rising liver enzymes. Any woman with right upper quadrant pain or upper abdominal pain in pregnancy needs these tests, regardless of blood pressure.
The only treatment for HELLP is delivery. Platelet transfusion may be needed before or during delivery if platelets fall to dangerous levels. Recovery after delivery is typically prompt — liver function and platelets usually normalise within days to a week. Recurrence in subsequent pregnancies is approximately 3–5% — lower than the recurrence rate for pre-eclampsia itself, but worth discussing with your obstetric team when planning future pregnancies.
Delivery is the only definitive treatment for pre-eclampsia. Timing involves balancing maternal risk against fetal maturity.
NICE broadly recommends: at or after 37 weeks — delivery recommended; 34–37 weeks — individualised decision based on severity and rate of deterioration; before 34 weeks — recommended if maternal condition is deteriorating, fetal compromise is developing, or blood pressure cannot be controlled. Corticosteroids and magnesium are given first where time allows.
Vaginal birth is not contraindicated in pre-eclampsia and is appropriate in many cases. Epidural anaesthesia is beneficial — it helps with blood pressure control and allows rapid intervention if needed. Caesarean section may be required if the clinical situation deteriorates too rapidly for induction to be appropriate.
Pre-eclampsia often worsens in the first 48–72 hours after delivery before improving — this is well-established and expected. Blood pressure monitoring continues intensively on the postnatal ward and women with severe pre-eclampsia may spend time in a high dependency unit immediately after delivery. Antihypertensive medication prescribed postnatally is compatible with breastfeeding (labetalol, nifedipine, enalapril) and may need to continue for weeks to months.
The 6-week postnatal review must include a blood pressure check. This is easy to skip or conduct incompletely — please attend it and specifically ask for your blood pressure to be taken and documented.
Pre-eclampsia has implications that extend well beyond the pregnancy itself — and most people are not told about them. This section covers what you need to know for your long-term health.
Pre-eclampsia is associated with significantly elevated lifetime cardiovascular risk. Women who have had pre-eclampsia have approximately:
This reflects shared underlying cardiovascular susceptibility rather than pre-eclampsia directly causing later disease. NICE recommends annual blood pressure and urine checks lifelong after pre-eclampsia. At your 6-week postnatal review and at future GP appointments, ensure your pre-eclampsia history is documented and that these checks are happening. Lifestyle factors that reduce cardiovascular risk — maintaining a healthy weight, regular physical activity, not smoking — are particularly relevant for women with a PE history.
Pre-eclampsia recurs in approximately 15–20% of subsequent pregnancies — higher if the first episode was early-onset or severe. In a subsequent pregnancy: aspirin 150mg from 12 weeks is strongly recommended; consultant-led care from booking is essential; first trimester PE screening where available provides important risk stratification; and an early conversation with your consultant about specific recurrence risk based on your history is worthwhile. Most women with a previous history of pre-eclampsia have subsequent pregnancies that are uncomplicated or well-managed.
Pre-eclampsia is frightening — often arriving suddenly when pregnancy was expected to be straightforward, sometimes resulting in emergency admission, premature birth, or time in intensive care. Post-traumatic stress following a severe pre-eclampsia experience is real. If you are struggling to process what happened — replaying events, experiencing anxiety about future pregnancy, finding it difficult to move forward — please speak to your GP. Psychological support after birth complications is appropriate and available.
Action on Pre-Eclampsia (apec.org.uk · helpline: 0800 1217227) is the UK charity specifically supporting those affected by pre-eclampsia — with information, a helpline, and peer support from others who have been through it.