Late Pregnancy · Hypertension
Preeclampsia Diagnosis & Management
When new high blood pressure + organ involvement after 20 weeks = preeclampsia. ACOG / ISSHP criteria, warning symptoms, treatment, delivery timing, recurrence in future pregnancies. NICE NG133 / ACOG.
Last reviewed 2 June 2026
Preeclampsia diagnostic criteria — ACOG 2020
Do I meet criteria for preeclampsia?
wk
Proteinuria
Severe features (any ONE = preeclampsia with severe features)
Enter gestational age and check the criteria.
Educational tool only — not medical advice. The ACOG 2020 criteria removed proteinuria as a mandatory diagnostic feature — end-organ damage (thrombocytopenia, liver/renal involvement, neurological symptoms) without proteinuria still establishes the diagnosis. If you have hypertension in pregnancy with ANY symptom on this list, contact your obstetric team or maternity assessment unit TODAY.
What does this mean?
Pre-eclampsia is a placental disease that affects 2–8 % of pregnancies and is a top global cause of maternal and perinatal mortality. The ACOG 2020 criteria removed proteinuria as mandatory: new hypertension after 20 wk + any end-organ damage (low platelets, elevated transaminases, renal dysfunction, pulmonary oedema, new headache/visual disturbance) is enough to diagnose. Severe features (BP ≥ 160/110, PLT < 100, Cr doubled, AST ≥ 2× ULN, pulmonary oedema, persistent headache or RUQ pain) trigger delivery if ≥ 34 wk, magnesium for seizure prophylaxis, and labetalol/nifedipine for severe BP. Definitive treatment is delivery — pre-eclampsia resolves over days– weeks postpartum, though up to a quarter develop NEW or worsening features after birth. Lifelong relevance: women with PE history have ~2× cardiovascular disease risk and need long-term BP / metabolic follow-up (NICE NG133, ESC 2024).
What is preeclampsia?
Pregnancy-only condition where blood pressure rises after 20 weeks AND organ function is affected. Affects 2-8% of pregnancies. Can occur up to 6 weeks postpartum.
Warning symptoms — when to call
Call midwife / GP today if:
- Severe headache not relieved by paracetamol.
- Visual changes — blurred vision, flashing lights, spots.
- Pain under right rib (liver).
- Sudden swelling face / hands / feet (overnight changes).
- Nausea / vomiting in 3rd trimester.
- Breathlessness.
- Home BP ≥140/90 on 2 readings 4h apart.
- Feeling “just not right”.
Diagnostic criteria (ACOG / ISSHP 2018)
NEW high BP (≥140/90 on 2 readings ≥4h apart) AFTER 20 weeks PLUS one of:
- Proteinuria (≥300 mg/24h, PCR ≥30 mg/mmol, ≥2+ dipstick).
- Kidney signs — creatinine raised.
- Liver signs — ALT >40 U/L.
- Low platelets <100,000.
- Neurological — severe headache, visual changes.
- Pulmonary oedema.
Severe PE: BP ≥160/110, severe symptoms, or severe organ dysfunction.
Gestational hypertension vs preeclampsia vs chronic
- Gestational hypertension: new high BP after 20 wk, NO organ involvement. ~25% progress to PE.
- Preeclampsia: high BP + organ involvement.
- Chronic hypertension: BP high BEFORE 20 weeks (often pre-pregnancy).
- Superimposed preeclampsia: chronic + new organ involvement — most aggressive.
Treatment
- Delivery is the only cure — timing balances mum + baby.
- BP control — labetalol first-line, nifedipine, hydralazine.
- Magnesium sulphate for seizure prevention if severe.
- Steroids for baby’s lungs if delivery <34 wk.
- Monitoring — frequent BP, urine, bloods, fetal CTG, growth scans.
- Hospital admission if severe.
Delivery timing
- Mild PE at term (37+): plan delivery now.
- Mild PE preterm: expectant with intensive monitoring; delivery 36-37 wk usually.
- Severe PE at term: immediate delivery.
- Severe PE 24-34 wk: 24-48h steroids then delivery.
- <24 wk severe: very difficult discussion.
Risks to baby
- Growth restriction (placenta delivering less).
- Preterm birth (often planned for safety).
- NICU admission.
- Stillbirth if severe/uncontrolled.
- Placental abruption.
Early detection + management minimises these. Most babies of PE mothers are fine.
Recurrence in future pregnancies
- Late-onset mild PE: ~15-20% recurrence.
- Severe PE: ~25-30%.
- Early-onset PE (<34 wk): ~30-50%.
- HELLP: ~25%.
Prevention for next pregnancy: aspirin 150 mg from <16 wk; calcium if low intake; preconception BP / BMI / HbA1c optimisation; APS antibody screen if recurrent / early-onset / severe.
Long-term picture
Increased lifetime risk:
- Hypertension (~3x).
- Heart disease (~2x).
- Stroke (~2x).
- Kidney disease.
- T2DM (~3x).
Annual BP, HbA1c, lipids, BMI follow-up.
Home BP monitoring
- Upper arm cuff (validated — Omron, A&D).
- Rest 5 min, sitting upright, arm supported.
- 3 readings 1 min apart, record middle.
- Morning + evening.
- 140/90+ on 2 readings 4h apart = call.
Different scenarios — preeclampsia
Scenario 1: 36 weeks, BP 145/95 + 2+ protein
PE confirmed. Admission. Labetalol if BP >150/100. Plan delivery within 24-48h.
Scenario 2: 28 weeks, BP 165/110 + severe headache
Severe PE. Hospital now. Magnesium sulphate. BP control. Steroids. Likely delivery within 24-48h.
Scenario 3: Day 3 postpartum, severe headache + BP 150/100
Postpartum PE. A&E. BP control. Magnesium if needed. Monitoring; BP often peaks 3-5 days postpartum.
Scenario 4: Chronic HTN, now 24 weeks, BP rising
Superimposed PE possible. Bloods, urine, fetal monitoring. Adjust BP medication. Watch for protein, organ signs.
Scenario 5: Previous PE, planning next pregnancy
Preconception consultant. Aspirin from <12 wk. Specialist care. Weekly BP / urine from 20 wk. Growth scans.
Care guidance — preeclampsia
- Routine BP + urine at every appointment.
- Home BP if at risk.
- Aspirin 150 mg from <16 wk if high-risk.
- Call midwife for warning symptoms.
- Don’t dismiss swelling, headache, visual changes.
- Delivery is cure.
- Magnesium sulphate for severe PE.
- Steroids if <34 weeks.
- Postpartum monitoring 24-72h+; BP can worsen.
- Long-term cardiovascular follow-up.
- Mental health support — PTSD common after severe PE.
Sources
- NICE NG133. Hypertension in pregnancy: diagnosis and management.
- ACOG Practice Bulletin 222. Gestational hypertension and preeclampsia.
- ISSHP. Hypertensive disorders of pregnancy: classification, diagnosis, and management recommendations 2018.
- Magpie Trial Collaborative Group. Magnesium sulphate for women with pre-eclampsia. Lancet 2002.
- Action on Pre-eclampsia (APEC) UK. action-on-pre-eclampsia.org.uk.
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Frequently asked questions
What is preeclampsia in simple terms?
PREGNANCY-ONLY condition where blood pressure rises AFTER 20 weeks and there's evidence your body's organs are being affected (kidneys leaking protein into urine; liver enzymes raised; low platelets; severe headache; visual disturbance). HAPPENS BECAUSE the placenta didn't bed into the womb properly in early pregnancy → leads to inflammation + blood vessel narrowing. AFFECTS 2-8% of pregnancies. CAN PROGRESS to eclampsia (seizures), HELLP (severe variant), stroke, placental abruption. NEEDS prompt diagnosis + management. POSSIBLE up to 6 weeks postpartum.
How is preeclampsia diagnosed?
ACOG / ISSHP 2018: NEW high blood pressure (≥140/90 on 2 readings ≥4 hours apart) AFTER 20 weeks PLUS one of: (1) PROTEIN in urine (≥300 mg/24h, OR protein:creatinine ratio ≥30 mg/mmol, OR ≥2+ dipstick); (2) KIDNEY signs — creatinine raised, no other cause; (3) LIVER signs — ALT >40 U/L; (4) LOW PLATELETS <100,000; (5) NEUROLOGICAL — severe headache, visual changes; (6) PULMONARY OEDEMA. Protein in urine NOT needed if other organ signs present. SEVERE PRE-ECLAMPSIA: BP ≥160/110, or severe symptoms, or severe organ dysfunction.
What are the warning symptoms?
CALL MIDWIFE / GP TODAY: (1) HEADACHE — severe, not relieved by paracetamol; (2) VISUAL CHANGES — blurred vision, flashing lights, spots; (3) PAIN under RIGHT RIB cage (liver); (4) SUDDEN swelling face / hands / feet (overnight changes worrying — gradual swelling normal); (5) NAUSEA / VOMITING in 3rd trimester (not normal morning sickness); (6) BREATHLESSNESS (pulmonary oedema); (7) HOME BP cuff reading 140/90+ on 2 readings 4 hours apart; (8) FEELING 'just not right'. AT-HOME readings useful for self-monitoring late pregnancy if at risk.
What's the difference between gestational hypertension and preeclampsia?
GESTATIONAL HYPERTENSION: NEW high BP after 20 wk WITHOUT proteinuria or organ involvement. ~25% PROGRESS to preeclampsia. Lower-risk, but still monitored. PREECLAMPSIA: high BP + organ involvement. Higher risk, more active management. CHRONIC HYPERTENSION: high BP existing BEFORE 20 weeks (often pre-pregnancy). SUPERIMPOSED PREECLAMPSIA: chronic + new organ involvement during pregnancy — most aggressive form. EACH has different management.
What treatment do I need?
(1) DELIVERY IS THE ONLY CURE — timing balances mum + baby; (2) BP CONTROL — labetalol first-line (oral or IV), nifedipine, hydralazine; (3) MAGNESIUM SULPHATE — for seizure prevention if severe; (4) STEROIDS for baby's lungs if delivery <34 weeks; (5) MONITORING — frequent BP, urine, bloods, fetal CTG, growth scans; (6) HOSPITAL admission if severe; (7) ASPIRIN 150 mg may continue. NICE NG133 protocols. AT TERM: deliver. PRETERM: balance — sometimes 'expectant management' to 34-37 weeks with intensive monitoring.
When will I deliver if I have preeclampsia?
DEPENDS ON SEVERITY + GESTATION: (1) MILD PE at term (37+): plan delivery now. (2) MILD PE preterm (28-36): expectant management with intensive monitoring if stable + baby OK; delivery 36-37 wk usually. (3) SEVERE PE at term (37+): IMMEDIATE delivery. (4) SEVERE PE 24-34 wk: 24-48h steroids for baby's lungs then delivery. (5) <24 wk: difficult; some terminate, some expectant; baby unlikely to survive at very early gestations. INDUCTION USUALLY tried; C-SECTION if unstable or other obstetric indication.
Will I need magnesium sulphate?
RECOMMENDED for SEVERE PE (BP ≥160/110, or symptoms, or severe organ dysfunction). PREVENTS ECLAMPSIA (seizures): ~50% reduction (Magpie trial 2002). NOT routinely for mild PE. GIVEN: IV loading dose (4g over 5-15 min) then maintenance infusion (1g/hr for 24h). FOR LABOUR + 24-48h post-delivery typically. SIDE EFFECTS: warmth, flushing, drowsiness, nausea (most), respiratory depression if overdose. MONITORING: BP, heart rate, urine output, reflexes, oxygen saturation. ALSO PROTECTIVE for baby brain if preterm.
Can I have a vaginal birth with preeclampsia?
USUALLY YES. NOT contraindicated. CONSIDERATIONS: (1) BP CONTROL maintained throughout labour; (2) CONTINUOUS CTG; (3) MAGNESIUM if severe PE; (4) AVOID prolonged labour — induction or C-section if not progressing; (5) EPIDURAL useful (reduces BP, helps with pain, improves placental flow) IF platelets adequate (>70-80,000); (6) AVOID NSAIDs postpartum (BP can rise); (7) POSTPARTUM monitoring 24-48h+ (BP often gets WORSE first 24-48h then improves over weeks). C-SECTION INDICATIONS: fetal distress, unstable maternal condition, other obstetric reasons.
Does preeclampsia affect baby?
RISKS to baby: (1) GROWTH RESTRICTION (placenta not delivering enough nutrients/oxygen) — slower growth, smaller baby; (2) PRETERM BIRTH (often planned for safety); (3) NICU admission; (4) STILLBIRTH risk if severe/uncontrolled; (5) PLACENTAL abruption (placenta separates early); (6) IUFD (intrauterine fetal death). EARLY DETECTION + management minimises these. MOST BABIES of PE mothers are fine, especially with prompt care. STEROIDS protective. MAGNESIUM neuroprotective. NEONATAL TEAM aware at delivery.
Will I get preeclampsia in next pregnancy?
RECURRENCE 15-65%, depending on severity + gestation of first episode: (1) Late-onset mild PE: ~15-20% recurrence; (2) Severe PE: ~25-30%; (3) Early-onset PE (<34 wk): ~30-50%; (4) HELLP: ~25%. PREVENTION FOR NEXT: aspirin 150 mg from <16 wk; calcium 1.5g/day if low intake; preconception BP, BMI, HbA1c optimisation; APS antibody screen if recurrent / early-onset / severe; specialist consultant care. EARLY + INTENSIVE monitoring.
Why does preeclampsia happen?
TWO-STAGE THEORY: (1) ABNORMAL PLACENTAL DEVELOPMENT — spiral arteries don't widen enough → placenta gets less blood; (2) PLACENTAL SIGNALS — release factors that damage maternal blood vessel walls throughout body → high BP, organ damage. RISK FACTORS: first pregnancy; previous PE; family history; chronic hypertension; T1DM/T2DM; lupus / APS; kidney disease; obesity (BMI ≥30); age ≥40; multiple pregnancy; PCOS; IVF. NOT YOUR FAULT — biological process you can't fully prevent.
What's the long-term impact?
INCREASED LIFETIME RISK of: (1) HYPERTENSION (~3x); (2) HEART DISEASE (~2x); (3) STROKE (~2x); (4) KIDNEY DISEASE; (5) T2DM (~3x); (6) METABOLIC SYNDROME. PREVENTION: annual BP checks; HbA1c, lipids, BMI; lifestyle measures; consider aspirin / statin in high-risk. POSITIVE: knowing risk means you can act. NICE recommends annual review after pre-eclampsia long-term. NOT INEVITABLE — many women never develop CVD.
Will I have side effects from BP medication?
(1) LABETALOL: most common; few side effects; safe in pregnancy + breastfeeding. (2) NIFEDIPINE: ankle swelling, headache, flushing initially; safe. (3) HYDRALAZINE: usually IV in acute setting; less common chronic. (4) METHYLDOPA: drowsiness, depression; older drug; still used. (5) AVOID: ACE inhibitors (ramipril, lisinopril) + ARBs (losartan) — teratogenic. CONTINUE during breastfeeding — labetalol, nifedipine, methyldopa all safe. SOME women need 2-3 medications combined.
What about home BP monitoring?
HOME BP MONITORING — useful in suspected / known PE. UPPER ARM CUFF (validated devices — Omron, A&D). PROCEDURE: rest 5 min, sitting upright, arm supported, take 3 readings 1 min apart, record middle. MORNING + evening. RANGE: <140/90 normal; 140/90+ on 2 readings 4h apart = call midwife. AT-HOME good for monitoring trends but ALWAYS verify with clinician for diagnostic decisions. WHITE-COAT effect can raise clinic readings — home readings sometimes more accurate.
Can I prevent preeclampsia?
REDUCE RISK: (1) ASPIRIN 150 mg nightly from <16 wk if high-risk (NICE / USPSTF guidance); (2) CALCIUM 1.5-2g/day if dietary intake low; (3) PRECONCEPTION BMI optimisation; (4) BP control before pregnancy; (5) MULTIDISCIPLINARY antenatal care; (6) MONITORING — BP, urine each visit; (7) SCREENING — FMF first-trimester screen identifies high-risk women. NOT all PE preventable — biological factors. RISK can be substantially reduced with proactive measures.
How does this relate to other calculators on BumpBites?
Companion: /calculators/preeclampsia-risk for risk assessment; /calculators/aspirin-pe-prevention for prophylaxis; /calculators/hellp-classifier for severe variant; /calculators/magnesium-sulphate for seizure prevention; /calculators/hypertensive-emergency-pregnancy; /calculators/antenatal-steroids if preterm; /calculators/fetal-weight for growth monitoring; /calculators/fmf-pe-screen for first-trimester screening.