Objective: To determine the effectiveness of aspirin to prevent preeclampsia in women identified as high risk for preeclampsia by an abnormal second-trimester uterine artery Doppler examination.
Data sources: Searches were conducted in MEDLINE, Embase, the Cochrane Controlled Trials Register, and Science Citation Index for randomized trials published from 1966 to 2000, using the following medical subject headings and key words: "aspirin," "antiplatelet*," "salicyl*," "acetylsalicyl*," "platelet aggregation inhibitors," "ultrasonography," "ultraso*," and "Doppler."
Study selection: We included all randomized trials that evaluated the effectiveness of aspirin compared with placebo or no treatment in women with an abnormal uterine artery Doppler and that reported clinically relevant perinatal and maternal outcomes. Study selection, quality assessment, and data extraction were performed in duplicate.
Tabulation, integration, and results: There were five relevant trials. Pooling of results from these trials showed a significant benefit of aspirin in reducing preeclampsia (odds ratio [OR] 0.55, 95% confidence interval [CI] 0.32, 0.95). The baseline risk of preeclampsia in women with abnormal uterine artery Doppler was 16%, and the number of women needed to be treated with aspirin to prevent one case of preeclampsia was 16 (95% CI 8, 316). Women on aspirin had babies who were on average 82 g heavier than controls, but this result did not reach statistical significance (weighted mean difference 81.5, 95% CI 40.27, 203.27).
Conclusion: Uterine artery Doppler assessment identifies high-risk women in whom aspirin therapy results in a significant reduction in preeclampsia.