Prediction and primary prevention of pre-eclampsia

Pre-eclampsia is associated with increased maternal and perinatal mortality and morbidity. Early recognition of women at risk of pre-eclampsia will enable the identification of high-risk women who may benefit from enhanced surveillance and prophylaxis. In this chapter, we summarise the accuracy of various tests used to predict the onset of pre-eclampsia and the effectiveness of preventative treatment. The tests used to predict pre-eclampsia include clinical history, examination findings, laboratory and haemodynamic tests. In general, tests in early pregnancy for predicting later development of pre-eclampsia have better specificity than sensitivity, as Body Mass Index greater than 34, alpha-fetoprotein, fibronectin and uterine artery Doppler (bilateral notching) all have specificities above 90%. Only uterine artery Doppler resistance index and combinations of indices have a sensitivity of over 60%. Test such as kallikreinuria not used in clinical practice, has shown high sensitivity above 80%, without compromising specificity, and require further investigation. None of the tests are sufficiently accurate to recommend them for routine use in clinical practice. The various treatment options for preventing pre-eclampsia include pharmacological agents, dietary supplementation and lifestyle modification. Antiplatelet agents, primarily low-dose aspirin, reduce the risk of pre-eclampsia by 10% (RR 0.90, 95% CI 0.84 to 0.97). Calcium effectively prevents pre-eclampsia (RR 0.45, 95% CI 0.31 to 0.65); the beneficial effect being observed in the high-risk group (RR 0.22; 95% CI 0.12 to 0.42) and in the group with low nutritional calcium intake (RR 0.36, 95% CI 0.20 to 0.65). Pharmacological agents, such as low molecular weight heparin, progesterone, nitric oxide donors, anti-hypertensive medication and diuretics are not effective in preventing pre-eclampsia. Dietary supplements, such as magnesium, anti-oxidants, marine oils and folic acid, do not reduce the incidence of pre-eclampsia. Evidence is lacking to support lifestyle preventative interventions for pre-eclampsia, such as rest, exercise and reduced dietary salt intake.