Aspirin reduces the risk of preterm preeclampsia when it is initiated at ≤16 weeks of gestation and at a daily dose of ≥100 mg; however, it does not reduce the risk of term preeclampsia, a recent study found. The systematic review and meta-analysis evaluated the prophylactic effect of aspirin during pregnancy. Researchers found:

• 16 trials including 18,907 participants provided data for preterm and term preeclampsia.
• Administration of aspirin was associated with reduction in the risk of preterm preeclampsia (relative risk [RR], 0.62), but there was no significant effect on term preeclampsia (RR, 0.92).
• The reduction in preterm preeclampsia was observed in the subgroup in which aspirin was initiated at ≤16 weeks’ gestation at a daily dose of ≥100 mg (RR, 0.33).