Early administration of low-dose aspirin for the prevention of severe and mild preeclampsia: a systematic review and meta-analysis.

OBJECTIVE To determine whether early administration of aspirin prevents severe and mild preeclampsia. STUDY DESIGN A systematic review and meta-analysis of randomized controlled trials were performed. Studies in which women were randomized at or before 16 weeks' gestation to low-dose aspirin versus placebo or no treatment were included. The outcomes of interest were severe preeclampsia and mild preeclampsia. Pooled relative risks with their 95% confidence intervals (CIs) were calculated. RESULTS Among 7941 citations retrieved, 352 were completely reviewed and four studies (392 women) fulfilled the inclusion criteria and were analyzed. When compared with controls, aspirin started at ≤16 weeks was associated with a significant reduction in severe (relative risk: 0.22, 95% CI: 0.08 to 0.57) but not mild (relative risk: 0.81, 95% CI: 0.33 to 1.96) preeclampsia. CONCLUSION Low-dose aspirin initiated at or before 16 weeks reduces the risk of severe preeclampsia, but not mild preeclampsia.