BACKGROUND AND PURPOSE:

• Use of low-dose aspirin early in pregnancy is associated with decreased risk of preeclampsia
• Abruption and antepartum hemorrhage may also be related to abnormal placentation, similar to preclampsia
• Roberge et al. (AJOG, 2017) assessed the effect of aspirin on the risk of placental abruption or antepartum hemorrhage, including the effect of gestational age at onset of therapy and dose

METHODS:

• A systematic review and meta-analysis
• Researchers analyzed randomized controlled trials evaluating the prophylactic effect of aspirin during pregnancy
• Relative risk (RR) of placental abruption or antepartum hemorrhage with their 95% confidence intervals (95% CI) were calculated
• Analyses were stratified according to
  • Daily dose of aspirin (<100 and ≥100 mg)
  • Gestational age of the onset of therapy (≤16 and >16 weeks)

RESULTS:

• 20 studies met inclusion criteria, totaling 12,585 participants
• Aspirin at a dose of <100 mg per day did not alter risk of placental abruption or antepartum hemorrhage
  • Initiation at ≤16 weeks: RR 1.11, 95% CI 0.52 to 2.36
  • Initiation at >16 weeks: RR 1.32, 95% CI 0.73 to 2.39
• Aspirin at a dose of ≥100 mg per day did not alter risk of placental abruption or antepartum hemorrhage
  • Initiation at ≤16 weeks: RR 0.62, 95% CI 0.31 to 1.26
    • Non-significant decreased risk
  • Initiation at >16 weeks: RR 2.08 95% CI 0.86 to 5.06
    • Non-significant increase risk
  • There was a significant difference when comparing these two subgroups (p=0.04)

CONCLUSION:

• The researchers note potential limitations, including lack of power, to assess subgroups and dose/timing of therapy
• In the ASPRE trail, prevention of preterm preeclampsia was dependent on compliance and this factor could not be assessed in the present meta-analysis
• A daily dose of aspirin of greater than 100 mg, initiated at less than 16 weeks of gestation may decrease risk of placental abruption or antepartum hemorrhage
• Based on previous studies and this current meta-analysis, initiating aspirin after 16 weeks will not only have no impact on preeclampsia but may increase risk of abruption or antepartum hemorrhage

Learn More – Primary Sources:

Meta-analysis on the effect of aspirin use for prevention of preeclampsia on placental abruption and antepartum hemorrhage