Pre - eclampsia

Pre-eclampsia is uniquely a disease occurring in the second half of pregnancy (after 20 weeks gestation) (1,2), and conventionally, characterised by pregnancy-induced hypertension, with proteinuria and often with oedema:

• NICE have defined pre-eclampsia as (2):
  • new onset of hypertension (over 140 mmHg systolic or over 90 mmHg diastolic) after 20 weeks of pregnancy and the coexistence of 1 or more of the following new-onset conditions:
    
    
    • proteinuria (urine protein:creatinine ratio of 30mg/mmol or more or albumin:creatinine ratio of 8mg/mmol or more, or at least 1 g/litre [2+] on dipstick testing) or
      
      
    • other maternal organ dysfunction:
      • renal insufficiency (creatinine 90 micromol/litre or more, 1.02 mg/100 ml or more)
      • liver involvement (elevated transaminases [alanine aminotransferase or aspartate aminotransferase over 40 IU/litre] with or without right upper quadrant or epigastric abdominal pain)
      • neurological complications such as eclampsia, altered mental status, blindness, stroke, clonus, severe headaches or persistent visual scotomata
      • haematological complications such as thrombocytopenia (platelet count below 150,000/microlitre), disseminated intravascular coagulation or haemolysis
        
        
    • uteroplacental dysfunction such as fetal growth restriction, abnormal umbilical artery doppler waveform analysis, or stillbirth
  • severe pre-eclampsia
    • pre-eclampsia with severe hypertension that does not respond to treatment or is associated with ongoing or recurring severe headaches, visual scotomata, nausea or vomiting, epigastric pain, oliguria and severe hypertension, as well as progressive deterioration in laboratory blood tests such as rising creatinine or liver transaminases or falling platelet count, or failure of fetal growth or abnormal doppler findings

NICE suggest that (1):

• blood pressure measurement and urinalysis for protein should be carried out at each antenatal visit to screen for pre-eclampsia
• at the booking appointment, the following risk factors for pre-eclampsia should be determined:
  
  
  • age 40 years or older
  • nulliparity
  • pregnancy interval of more than 10 years
  • family history of pre-eclampsia
  • previous history of pre-eclampsia
  • body mass index 30 kg/m2 or above
  • pre-existing vascular disease such as hypertension
  • pre-existing renal disease
  • multiple pregnancy
    
    
  • more frequent blood pressure measurements should be considered for pregnant women who have any of the above risk factors
• the presence of significant hypertension and/or proteinuria should alert the healthcare professional to the need for increased surveillance
• hypertension in which there is a single diastolic blood pressure of 110 mmHg or two consecutive readings of 90 mmHg at least 4 hours apart and/or significant proteinuria (1+) should prompt increased surveillance
• if the systolic blood pressure is above 160 mmHg on two consecutive readings at least 4 hours apart, treatment should be considered
• all pregnant women should be made aware of the need to seek immediate advice from a healthcare professional if they experience symptoms of pre-eclampsia. Symptoms include:
  • severe headache
  • problems with vision, such as blurring or flashing before the eyes
  • severe pain just below the ribs
  • vomiting
  • sudden swelling of the face, hands or feet

Notes:

• hypertensive disorders during pregnancy may also result in substantial maternal morbidity
  • a UK study reported that one-third of severe maternal morbidity was a consequence of hypertensive conditions
  • a study from one region of the UK reported that 1 in 20 (5%) women with severe pre-eclampsia or eclampsia were admitted to intensive care
• hypertensive disorders also carry a risk for the baby (2)
  • the most recent UK perinatal mortality report, 1 in 20 (5%) stillbirths in infants without congenital abnormality occurred in women with pre-eclampsia
  • the contribution of pre-eclampsia to the overall preterm birth rate is substantial;
    • 1 in 250 (0.4%) women in their first pregnancy will give birth before 34 weeks as a consequence of pre-eclampsia and 8-10% of all preterm births result from hypertensive disorders
    • half of women with severe pre-eclampsia give birth preterm
    • small-for-gestational-age babies (mainly because of fetal growth restriction arising from placental disease) are common, with 20-25% of preterm births and 14-19% of term births in women with pre-eclampsia being less than the tenth centile of birth weight for gestation

Reference:

1. NICE (March 2016). Antenatal care for uncomplicated pregnancies
2. NICE (June 2019). Hypertension in pregnancy - the management of hypertensive disorders during pregnancy