Is it safe to take aspirin (acetylsalicylic acid) during pregnancy?

Aspirin Use During Pregnancy

Low-dose aspirin (81-100 mg daily) is safe and recommended during pregnancy only for specific high-risk populations, while regular-dose aspirin should be avoided, especially in the third trimester due to potential complications during delivery.

General Safety Considerations

• Regular-dose aspirin is contraindicated during the last trimester of pregnancy as it may cause problems in the unborn child or complications during delivery 1
• Aspirin at doses >100 mg daily is not recommended during routine pregnancy due to potential bleeding risks

Appropriate Use of Low-Dose Aspirin in Pregnancy

Recommended for:

1. Women with high risk for preeclampsia:

   • Those with type 1 or type 2 diabetes 2
   • History of preeclampsia, especially early-onset (<34 weeks)
   • Chronic hypertension
   • Autoimmune diseases (especially SLE) 2
   • Renal disease
   • Multifetal gestation

2. Women with moderate risk factors (when multiple factors present):

   • First pregnancy
   • Age ≥35 years
   • BMI >30 kg/m²
   • Family history of preeclampsia
   • Nulliparity 2

Dosage and Timing:

• Dosage: 81-100 mg daily 2, 3
  • For women with diabetes, 100-150 mg daily is recommended 2
  • Current US formulations typically available as 81 mg tablets
• Timing: Start between 12-16 weeks gestation (optimally before 16 weeks) 2, 3
• Duration: Continue until delivery 3

Important Caveats and Contraindications

• Low-dose aspirin should be discontinued prior to delivery based on the obstetrician and anesthesiologist's assessment 2
• Regular-dose aspirin should be avoided during pregnancy, especially in the third trimester 1
• Aspirin is contraindicated in women with:
  • History of aspirin allergy
  • Bleeding disorders
  • Active peptic ulcer disease

Evidence Quality and Considerations

• The recommendation for low-dose aspirin in high-risk women is supported by multiple guidelines including the American College of Obstetricians and Gynecologists, US Preventive Services Task Force, and American College of Rheumatology 2, 3
• Low-dose aspirin has been shown to reduce the risk of preeclampsia in high-risk women 3, 4
• In women without high-risk factors for preeclampsia, evidence does not support the use of prophylactic low-dose aspirin for prevention of early pregnancy loss, fetal growth restriction, stillbirth, or preterm birth 3
• Some evidence suggests that starting aspirin before 12 weeks may be beneficial and safe 5, but most guidelines recommend starting at 12-16 weeks

Common Pitfalls to Avoid

• Starting aspirin too late (after 16 weeks) may reduce effectiveness 6
• Using regular-dose aspirin instead of low-dose formulations
• Continuing regular-dose aspirin into the third trimester
• Prescribing aspirin for all pregnant women without risk stratification
• Failing to discontinue aspirin before delivery when indicated by the clinical situation

Remember that the decision to use low-dose aspirin should be made in consultation with an obstetrician based on individual risk factors for preeclampsia and other pregnancy complications.