Prevention of preeclampsia: a big disappointment.

Preeclampsia is a multisystem disorder of unknown etiology. During the past 2 decades, numerous clinical reports and randomized trials described the use of various methods to prevent or reduce the incidence and severity of preeclampsia. These methods were used in an attempt to correct certain abnormalities such as biochemical imbalance, a pathophysiologic mechanism, or a dietary deficiency. There are at least 15 randomized trials evaluating the use of various antihypertensive drugs including diuretics for the prevention of preeclampsia. Results of these trials reveal no such benefit. There are few randomized trials evaluating magnesium (n = 2), zinc (n = 2), or fish oil supplementation (n = 3) to prevent preeclampsia. The majority of these trials had limited sample size; however, results reveal minimal-to-no benefit. There are 7 placebo-controlled trials evaluating calcium supplementation during pregnancy. Findings of these trials reveal that calcium supplementation does not reduce the incidence of preeclampsia in healthy nulliparous women. The majority of randomized trials for the prevention of preeclampsia have used low-dose aspirin. Results of early single-center trials demonstrated an average reduction of preeclampsia of 70% with low-dose aspirin. However, results of recent large multicenter trials (n = 7) that included >27,000 women revealed minimal-to-no benefit. Until the pathogenesis of preeclampsia is well defined, prevention of this syndrome with any modality remains unlikely.