PatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
- Pre-eclampsia is pregnancy-induced hypertension in association with proteinuria (>0.3 g in 24 hours) with or without oedema. Virtually any organ system may be affected.
- Pre-eclampsia is a relatively common condition but may become life-threatening for the mother and the fetus. It is characterised by maternal hypertension, proteinuria, oedema, fetal intrauterine growth restriction and premature birth.
- Severe pre-eclampsia is defined as diastolic blood pressure of at least 110 mm Hg, or systolic blood pressure of at least 160 mm Hg, and/or symptoms, and/or biochemical and/or haematological impairment.
- In severe pre-eclampsia, the fetus and/or newborn may have neurological damage induced by hypoxia. Prompt recognition of pre-eclampsia and any signs of clinical deterioration, including a reduction in platelet count, necessitates urgent referral to secondary care to avoid the serious clinical consequences of these conditions.
- Eclampsia is defined as the occurrence of one or more convulsions superimposed on pre-eclampsia.
- Severe pre-eclampsia and eclampsia are relatively rare but serious complications of pregnancy. They are the second leading cause of direct maternal deaths in the UK.
- The incidence of severe pre-eclampsia is about 5/1,000 maternities. The incidence of eclampsia in the UK is around 1/2000 pregnancies.
- 44% of seizures occur postnatally, the remainder being antepartum (38%) or intrapartum (18%).
- The most recent audit of maternal deaths in the UK reported 22 deaths from pre-eclampsia, of which 20 were associated with substandard care and 14 were thought to be avoidable.
The following are at high risk of developing pre-eclampsia:
- First pregnancy, or first pregnancy with a new partner.
- Pre-eclampsia or eclampsia in any previous pregnancy.
- 10 years or more since the last baby.
- Age 40 years or more.
- Body mass index (BMI) of 35 or more at presentation.
- Family history of pre-eclampsia (in mother or sister).
- Certain underlying medical conditions:
- Pre-existing hypertension.
- Pre-existing renal disease.
- Pre-existing diabetes.
- Antiphospholipid antibodies present.
- The aetiology and pathogenesis of pre-eclampsia still remain poorly understood.
- It is characterised by suboptimal uteroplacental perfusion associated with a maternal inflammatory response and maternal vascular endothelial dysfunction.
- The placenta has a pivotal role in the pathogenesis of pre-eclampsia.
Pre-eclampsia occurs when blood pressure is >140/90 mm Hg in the second half of pregnancy, with ≥1+ proteinuria on reagent stick testing.
- New hypertension.
- New and/or significant proteinuria.
- Other clinical features of severe pre-eclampsia include:
- Severe headache - usually frontal.
- Sudden swelling of face, hands and feet.
- Liver tenderness.
- Visual disturbance (eg, blurring or flashing lights in front of the eyes).
- Platelet count falling to below 100 x 109/L (a falling platelet count predicts severe disease and these women need urgent referral and further investigation).
- Epigastric pain and/or vomiting.
- Abnormal liver enzymes (ALT or AST rising to above 70 IU/L).
- HELLP syndrome: H (haemolysis) EL (elevated liver enzymes) LP (low platelets).
- Fetal distress - reduced fetal movements.
- Small for gestational age infant.
- Approximately 45% of cases of eclampsia occur after delivery, most by four days postpartum but occasionally they can be up to four weeks later.
Blood pressure measurement
- Use a sitting or semi-reclining position so that the arm to be used is at the level of the heart.
- Do not take the blood pressure in the upper arm with the woman on her side, as this will give falsely lower readings.
These tests should be performed in secondary care:
- Urinalysis: send for microscopy, culture and sensitivities if proteinuria is present.
- Frequent monitoring of FBC, LFTs, renal function, electrolytes and serum urate: to identify rising values to help guide the decision as to when to deliver.
- Clotting studies if there is severe pre-eclampsia or thrombocytopenia.
- 24-hour urine collections for protein quantification and creatinine clearance.
- Cerebral imaging (MRI or CT) is not indicated in uncomplicated eclampsia. However, imaging is necessary to exclude haemorrhage and other serious abnormalities in women with focal neurological deficits or prolonged coma.
- Assessment of fetus -ultrasound assessment of fetal growth and the volume of amniotic fluid; and Doppler velocimetry of umbilical arteries.
NB: pre-eclampsia can be difficult to diagnose in women with pre-existing hypertension, especially if there is pre-existing renal disease with proteinuria. Under these circumstances, pre-eclampsia can present in the second half of pregnancy with a surge in blood pressure or proteinuria, or with other features such as thrombocytopenia, a raised level of liver transaminases, and reduced fetal growth.
- Management in hospital is multidisciplinary with involvement of the obstetric team, anaesthetics and haematology, liaison with paediatrics, and appropriate arrangements for in-utero transfer if required and once the woman's condition is stable.
- Patients can be managed conservatively if they are less than 34 weeks, haemodynamically stable, without coagulation abnormalities and in the absence of HELLP.
- Delivery of the placenta is the only cure for pre-eclampsia.
Frequency of community monitoring
- The National Institute for Health and Clinical Excellence (NICE) recommends that more frequent blood pressure measurements should be considered for pregnant women who have any of the risk factors for pre-eclampsia, and that the presence of significant hypertension and/or proteinuria should alert the healthcare professional to the need for increased surveillance.
- No predisposing factors for pre-eclampsia: 24 weeks of gestation to delivery - follow local protocols and the NICE antenatal guideline for low-risk multiparous women.
- One predisposing factor listed above, but no factor that requires referral in early pregnancy (listed below):
- 24 to 32 weeks of gestation: minimum standard no more than a three-week interval between assessments, adjusted to individual needs and any changes during pregnancy.
- 32 weeks of gestation to delivery: minimum standard no more than two-week interval between assessments, adjusted to individual needs and any changes during pregnancy.
Women should be admitted if they have:
- Systolic blood pressure ≥160 mm Hg.
- Diastolic blood pressure ≥100 mm Hg.
- Raised blood pressure with proteinuria ≥+1.
- Any clinical symptoms or signs of pre-eclampsia.
Management of severe pre-eclampsia
Delivery of the fetus and placenta is the only cure. However, preterm delivery may adversely affect neonatal outcome, with complications resulting from prematurity and low birth weight.
- Blood pressure:
- Antihypertensive treatment should be started in women with a systolic blood pressure over 160 mm Hg or a diastolic blood pressure over 110 mm Hg. In women with other markers of potentially severe disease, treatment can be considered at lower degrees of hypertension.
- Labetalol (given orally or intravenously), oral nifedipine or intravenous hydralazine are usually given for the acute management of severe hypertension.
- Atenolol, angiotensin-converting enzyme (ACE) inhibitors, angiotensin-II receptor antagonists and diuretics should be avoided.
- Antihypertensive medication should be continued after delivery, as dictated by the blood pressure. It may be necessary to maintain treatment for up to three months, although most women can have treatment stopped before this.
- Prevention of seizures:
- Magnesium sulfate should be considered when there is concern about the risk of eclampsia.
- In women with less severe disease, the decision is less clear and will depend on individual case assessment.
- Control of seizures:
- Magnesium sulfate is the therapy of choice to control seizures. A loading dose of 4 g is given by infusion pump over 5-10 minutes, followed by a further infusion of 1 g/hour maintained for 24 hours after the last seizure.
- Recurrent seizures should be treated with either a further bolus of 2 g magnesium sulfate or an increase in the infusion rate to 1.5 g or 2.0 g/hour.
- Fluid balance:
- Fluid restriction is advisable to reduce the risk of fluid overload in the intrapartum and postpartum periods. Total fluids should usually be limited to 80 ml/hour or 1 ml/kg/hour.
- The decision to deliver should be made once the woman is stable and with appropriate senior personnel present.
- If the fetus is less than 34 weeks of gestation and delivery can be deferred, corticosteroids should be given, although after 24 hours the benefits of conservative management should be reassessed.
- Conservative management at very early gestations may improve the perinatal outcome but must be carefully balanced with maternal well-being.
- The mode of delivery should be determined after considering the presentation of the fetus and the fetal condition, together with the likelihood of success of induction of labour after assessment of the cervix.
- The third stage should be managed with 5 units of intramuscular/slow intravenous Syntocinon®. Ergometrine and Syntometrine® should not be given for prevention of haemorrhage, as this can further increase the blood pressure.
- Prophylaxis against thromboembolism should be considered.
Management of eclampsia
- The patient should be placed in the left lateral position and the airway secured.
- Oxygen should be administered.
- Treatment and prophylaxis of seizures:
- Magnesium sulfate is the anticonvulsant drug of choice.
- Intubation may become necessary in women with repeated seizures in order to protect the airway and ensure adequate oxygenation.
- Treatment of hypertension:
- Reduction of severe hypertension (blood pressure >160/110 mm Hg or mean arterial pressure >125 mm Hg) is essential to reduce the risk of cerebrovascular accident. Treatment may also reduce the risk of further seizures.
- Intravenous hydralazine or labetalol are the two most commonly used drugs. Both may precipitate fetal distress and therefore continuous fetal heart rate monitoring is necessary.
- Fluid therapy:
- Close monitoring of fluid intake and urine output is mandatory.
- Pre-loading the circulation with 400-500 ml colloid prior to regional anaesthesia or vasodilatation with hydralazine may reduce the risk of hypotension and fetal distress.
- The definitive treatment of eclampsia is delivery. Attempts to prolong pregnancy in order to improve fetal maturity are unlikely to be of value.
- However, it is unsafe to deliver the baby of an unstable mother even if there is fetal distress. Once seizures are controlled, severe hypertension treated and hypoxia corrected, delivery can be expedited.
- Vaginal delivery should be considered but Caesarean section is likely to be required in primigravidae, well before term and with an unfavourable cervix.
- After delivery, high-dependency care should be continued for a minimum of 24 hours.
All patients need careful follow-up and a formal postnatal review to establish if there is chronic hypertension, proteinuria or liver damage.
- Eclampsia is usually part of a multisystem disorder. Associated complications include haemolysis, HELLP syndrome (3%), disseminated intravascular coagulation (3%), renal failure (4%) and adult respiratory distress syndrome (3%).
- Pre-eclampsia can progress to eclampsia with epileptic fits and sometimes other neurological symptoms, including focal motor deficits and cortical blindness.
- Cerebrovascular haemorrhage is a complicating factor in 1-2%.
- Pre-eclampsia is also associated with fetal growth restriction, low birth weight, preterm delivery, small for gestational age infants and respiratory distress syndrome.
- The maternal mortality rate of eclampsia is 1.8%.
- Pre-eclampsia recurs in around 15% of women who had pre-eclampsia in their first pregnancy, although this risk may be as high as 25% if the pre-eclampsia led to birth before 34 weeks and as high as 50% if birth was before 28 weeks.
- Women who have had pre-eclampsia are at an increased risk of hypertension and heart disease in later life.
- There is an increased risk of cardiovascular death in women with preterm pre-eclampsia in their first pregnancy and who have no subsequent children.
- Identification and appropriate action for those women with known risk factors at booking.
- Early recognition and appropriate action for those women with symptoms and signs of pre-eclampsia.
- Calcium supplementation in pregnancy has been shown to approximately halve the risk of pre-eclampsia.
- Antiplatelet agents - eg low-dose aspirin, have moderate benefits when used for prevention of pre-eclampsia.
- However, their use is still controversial. One study has shown that low dose aspirin has a small effect in the prevention of pre-eclampsia in women considered to be at high risk for the disease but it was not effective in reducing the risk in those at low-risk.
Further reading & references
- Carson MP et al; Hypertension and Pregnancy, Medscape, Feb 2012
- Managment of Severe Pre-Eclampsia and Eclampsia, Guidelines & Audit Implementation Network (2012)
- Saving Mothers' Lives. Reviewing maternal deaths to make motherhood safer: 2006-2008; Centre for Maternal and Child Enquiries (CMACE), BJOG, Mar 2011
- Williams D, Craft N; Pre-eclampsia. BMJ. 2012 Jul 19;345:e4437. doi: 10.1136/bmj.e4437.
- Antenatal care; NICE Clinical Guideline (March 2008)
- Johnson DD; Induced labour for pre-eclampsia and gestational hypertension. Lancet. 2009 Aug 3.
- Hernandez-Diaz S, Toh S, Cnattingius S; Risk of pre-eclampsia in first and subsequent pregnancies: prospective cohort study. BMJ. 2009 Jun 18;338:b2255. doi: 10.1136/bmj.b2255.
- Bellamy L, Casas JP, Hingorani AD, et al; Pre-eclampsia and risk of cardiovascular disease and cancer in later life: systematic review and meta-analysis. BMJ. 2007 Nov 10;335(7627):974. Epub 2007 Nov 1.
- Skjaerven R, Wilcox AJ, Klungsoyr K, et al; Cardiovascular mortality after pre-eclampsia in one child mothers: prospective, population based cohort study. BMJ. 2012 Nov 27;345:e7677. doi: 10.1136/bmj.e7677.
- Hofmeyr GJ, Lawrie TA, Atallah AN, et al; Calcium supplementation during pregnancy for preventing hypertensive disorders Cochrane Database Syst Rev. 2010 Aug 4;8:CD001059.
- Duley L, Henderson-Smart Dj, Meher S, et al; Antiplatelet agents for preventing pre-eclampsia and its complications. Cochrane Database Syst Rev. 2007 Apr 18;(2):CD004659.
- Trivedi NA; A meta-analysis of low-dose aspirin for prevention of preeclampsia. J Postgrad Med. 2011 Apr-Jun;57(2):91-5. doi: 10.4103/0022-3859.81858.
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Dr Colin Tidy
Dr Louise Newson
Dr John Cox