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Optimal regimen of aspirin to prevent preeclampsia may also prevent placental abruption or antepartum hemorrhage
Clinical Question
Does aspirin to prevent preeclampsia also prevent placental abruption or antenatal hemorrhage?
Bottom line
Taking aspirin to prevent preeclampsia, at a dosage of at least 100 mg daily, is significantly associated with a reduced risk of placental abruption or antenatal hemorrhage when started no later than at 16 weeks' gestation as compared with a start later in the pregnancy, based on a meta-analysis of studies for which these were not the primary outcomes. Further studies are needed to reach a sample size necessary to establish whether this regimen is superior to placebo for the prevention of placental abruption or antenatal hemorrhage. 1a-
Reference
Study design: Meta-analysis (randomized controlled trials)
Funding: Government
Setting: Various (meta-analysis)
Synopsis
Previous meta-analyses of randomized controlled trials showed that taking aspirin for the prevention of preeclampsia is only effective if used at a dosage of at least 100 mg daily beginning before 16 weeks' gestation. The objective of this meta-analysis was to assess the effect of aspirin on the risk of placental abruption or antepartum hemorrhage with regard to both dose and gestational age at initiation of therapy. The studies selected for this meta-analysis included 20 trials with 11,585 participants in which aspirin or dipyridamole was compared with placebo or no treatment for the prevention of preeclampsia. Studies were excluded if the pregnant women began treatment before pregnancy or if they already had preeclampsia or fetal growth restriction at the time of randomization. Abruption occurred in 1.5% of cases. When aspirin was used at a dosage of less than 100 mg daily there was no effect on the risk of placental abruption or antepartum hemorrhage. At a dosage of aspirin 100 mg or more daily, there was a significant difference between the risk of abruption or hemorrhage when treatment was started before 16 weeks' compared with after 16 weeks' (P = .04). However, neither subgroup reached statistical significance compared with placebo (relative risk [RR] 0.64, 95% CI 0.31 - 1.26 and RR 2.08, 0.86 - 5.06, respectively). The relative risks are arguably clinically meaningful differences. The wide confidence intervals are in the context of the fact that placental abruption and antenatal hemorrhage are relatively rare outcomes, and statistical power is still lacking. Larger sample sizes are needed to demonstrate whether the relative risks might provide statistically significant results.
Reviewer
Linda Speer, MD
Professor and Chair, Department of Family Medicine
University of Toledo
Toledo, OH
Comments
I am familiar with using ASA for women with previous pregnancy loss or previous preeclampsia. Are we recommending routine use in pregnant women?
Aspirin
Optimal aspirin dose for the prevention of antepartum hemorrhage is quite informative for me. This will change my practice and initiate discussions on this with my patients.