Aspirin Reduces Risk for Preeclampsia, but Who Should Be Treated?

The poorly understood etiology of preeclampsia seems to involve inflammation, placental damage, prostaglandin imbalance, and activation of platelets and the clotting system. Some early trials suggested that antiplatelet agents might prevent or delay preeclampsia, but subsequent larger studies suggested that the benefits were modest at best. Investigators have now combined unpublished individual patient data from 31 primary-prevention trials in which more than 32,000 pregnant women at risk for preeclampsia were randomized to receive one or more antiplatelet agents (primarily aspirin), a placebo, or no treatment.

Antiplatelet agents were associated with a 9% to 10% reduction in relative risk for each of four major outcomes (preeclampsia, deliv…