Early Administration of Low-Dose Aspirin for the Prevention of Preterm and Term Preeclampsia: A Systematic Review and Meta-Analysis

<b><i>Objective:</i></b> To compare the effect of early administration of aspirin on the risk of preterm and term preeclampsia. <b><i>Method:</i></b> A systematic review and meta-analysis of randomized controlled trials were performed. Women who were randomized to low-dose aspirin or placebo/no treatment at or before 16 weeks of gestation were included. The outcomes of interest were preterm preeclampsia (delivery <37 weeks) and term preeclampsia. Pooled relative risks (RR) with their 95% confidence intervals (CI) were computed. <b><i>Results:</i></b> The search identified 7,941 citations but only five trials on a combined total of 556 women fulfilled the inclusion criteria. When compared to controls, aspirin initiated ≤16 weeks of gestation was associated with a major reduction of the risk of preterm preeclampsia (RR 0.11, 95% CI 0.04–0.33) but had no significant effect on term preeclampsia (RR 0.98, 95% CI 0.42–2.33). <b><i>Conclusion:</i></b> Low-dose aspirin administrated at or before 16 weeks of gestation reduces the risk of preterm but not term preeclampsia.