BACKGROUND AND PURPOSE:

• Hastie et al. (AJOG, 2020) investigated whether aspirin use during pregnancy is associated with an increased risk of bleeding complications

METHODS:

• Register-based cohort study
• Data sources
  • Swedish Pregnancy Register
  • Combines prospectively collected data (from the first prenatal visit to postpartum follow-up)
• Participants
  • Delivery between January 2013 to July 2017
• Exposure
  • Self-reported use of aspirin at any time during pregnancy
• Study design
  • The authors used logistic regression to assess the risk of hemorrhage
    • Antepartum | Intrapartum | Postpartum
  • Odds ratio (OR) was calculated and adjusted for confounding
• Primary outcome
  • Bleeding complications recorded in prenatal or delivery records

RESULTS:

• A total of 313,624 women gave birth during the study period
  • Aspirin use during pregnancy: 1.3%

Antepartum

• Aspirin use was not associated with bleeding complications during the antepartum period
  • adjusted OR: 1.22 (95% CI, 0.97 to 1.54)

Intrapartum

• Aspirin was associated with a higher incidence of intrapartum hemorrhage (cases of placenta previa and abruption were excluded from analyses)
  • Aspirin users: 2.9%
  • Non-users: 1.5%
  • aOR 1.63 (95% CI, 1.30 to 2.05)

Postpartum

• PPH
  • Aspirin users: 10.2%
  • Non-users: 7.8%
  • aOR 1.23 (95% CI 1.08 to 1.39)
• Aspirin was associated with increased risk for postpartum hematoma
  • Aspirin users: 0.4%
  • Non-users: 0.1%
  • aOR 2.21 (95% CI, 1.13 to 4.34)

Neonatal

• The risk of a neonatal intracranial hemorrhage was also increased with aspirin use (adjusted for gestational age at delivery and mode of delivery)
  • Aspirin users: 0.07%
  • Non-users: 0.01%
  • aOR 9.66 (95% CI, 1.88 to 49.48)

Note: Higher incidence of bleeding associated with aspirin was found in women with vaginal birth and not caesarean

CONCLUSION:

• In women who delivery vaginally, aspirin use during pregnancy was associated with an increased risk for intra and postpartum hemorrhage as well as neonatal intracranial bleeding
• Authors recognize limitation that aspirin dose not recorded
  • However, Swedish guidelines recommend 75 mg of aspirin daily after 12 weeks for preterm preeclampsia prevention
  • Therefore, the assumption is that most aspirin users in this cohort would be taking a 75 mg per day dose
• The authors conclude that

When offering aspirin during pregnancy these risks need to be weighed against the potential benefits

Learn More – Primary Sources:

Aspirin use during pregnancy and the risk of bleeding complications: A Swedish population-based cohort study.

Related ObG Topics:

ASPRE Trial: A Combined Risk Algorithm and Use of Aspirin to Prevent Preterm Preeclampsia

ASPIRIN RCT Results: Low-Dose Aspirin in Early Pregnancy and Impact on Preterm Delivery and Perinatal Mortality