Antiplatelet agents prevent preeclampsia

Clinical Question

Do antiplatelet agents prevent preeclampsia in high-risk women?

Bottom Line

In women at increased risk of developing preeclampsia, antiplatelet therapy (primarily aspirin) modestly decreases the rate of developing preeclampsia, the rate of delivering before 34 weeks', and the overall rate of poor outcomes, without increasing the risk of bleeding complications. (LOE = 1a)


Askie LM, Duley L, Henderson-Smart DJ, Stewart LA; PARIS Collaborative Group. Antiplatelet agents for prevention of pre-eclampsia: a meta-analysis of individual patient data. Lancet 2007;369:1791-1798.  [PMID:17512048]

Study Design

Meta-analysis (randomized controlled trials)




Various (meta-analysis)


The authors searched multiple databases to identify randomized controlled trials of antiplatelet agents (aspirin or dipyridamole) given to women at risk of developing preeclampsia. Additionally, they attempted to locate unpublished studies by asking experts in the field. At least 2 researchers assessed potentially eligible studies for inclusion and resolved any discrepancies by discussion. Women were considered to be at risk of developing preeclampsia if they had gestational hypertension, intrauterine growth retardation, a pre-existing medical condition (eg, renal disease, diabetes, immune disorder, chronic hypertension), or obstetric risk factors early in their current pregnancy (eg, being a primigravida or a having multiple pregnancy). The researchers identified 38,026 patients in 63 eligible trials, but were only able to obtain data for 34,288 (90% of the potential pool) from 36 trials. In this paper, they report only on the 32,217 women recruited for primary prevention. Approximately 90% of the included women had at least one risk factor for preeclampsia. The authors used intention-to-treat analysis to assess the outcomes in the mothers and the babies. Twenty seven studies accounted for 98% of the women. In those studies, the active treatment group took aspirin (50 mg to 150 mg daily). In the remainder of the studies, the women in the active treatment group took aspirin plus dipyridamole, dipyridamole alone, heparin, or ozagrel. Antiplatelet therapy modestly reduced the rate of developing preeclampsia (7.9% vs 8.7%; number needed to treat [NNT] = 118; 95% CI, 69-433). Additionally there were modest benefits in preventing delivery before 34 weeks of gestation (6.5% vs 7.2%; NNT = 148; 81-850) and pregnancies with serious adverse outcomes (preeclampsia, premature delivery, fetal/neonatal death, small-for-gestational-age infants, or maternal death; 17.9% vs 19.7%; NNT = 54; 34-144). Although there were slight decreases in fetal/neonatal death (3.1% vs 3.4%) and small-for-gestational-age infants (5.3% vs 5.9%), these were not statistically significant. Finally, there was no significant difference in bleeding complications.