Prediction and prevention of pregnancy-induced hypertensive disorders.

Because hypertensive disorders complicating pregnancy are common and constitute a leading cause of maternal, fetal and neonatal morbidity and mortality, prevention attempts appear to be justified. Primary prevention is only possible by avoiding pregnancy. Secondary prevention requires identification of patients at risk. A large number of predictive methods have been published and the majority appear to be of no or limited value. At present only the determination of inactive urinary kallikrein and uteroplacental colour-pulsed Doppler velocimetry show promise and require further assessment. Analysis of the many interventions advocated for prevention of pre-eclampsia reveals that only dietary calcium supplementation and prophylactic low-dose aspirin have shown promise of efficacy in small controlled clinical trials, but the results of large, multicentre trials are disappointing. The disappointing results obtained in large, multicentre trials may be explained, at least in part, by the lack of strict eligibility criteria and end-points and by low patient compliance. Prophylactic low-dose aspirin is recommended in women at high risk because it is associated with a moderate reduction in risk, may reduce the severity of pre-eclampsia if it develops and appears to be safe for mother and infant. The present data do not support any prophylactic intervention in pregnant women at low or medium risk.