I am a postpartum breastfeeding woman prescribed low‑dose (81 mg) aspirin for six weeks—should I continue it to prevent thrombophilia?

Postpartum Low-Dose Aspirin for Thrombophilia Prevention

You should discontinue the low-dose aspirin at 6 weeks postpartum as prescribed, unless you have specific high-risk thrombophilia or prior venous thromboembolism (VTE), in which case low-molecular-weight heparin (LMWH)—not aspirin—is the appropriate thromboprophylaxis.

Understanding Aspirin's Role in the Postpartum Period

Low-dose aspirin (81 mg) is primarily indicated during pregnancy and the immediate postpartum period for preeclampsia prevention, not for venous thromboembolism (VTE) prophylaxis 1, 2. The American College of Obstetricians and Gynecologists recommends aspirin for women at high risk of preeclampsia, initiated between 12–28 weeks of gestation and continued until delivery 1, 2.

• For preeclampsia prevention: Aspirin is continued until delivery or up to 6 weeks postpartum in specific high-risk scenarios 3
• For VTE prevention: Aspirin alone is insufficient for thromboprophylaxis in high-risk patients and does not provide adequate protection against VTE 4

When to Stop Aspirin Postpartum

The 6-week postpartum endpoint you were prescribed aligns with standard practice for certain conditions:

• Myeloproliferative neoplasms (polycythemia vera, essential thrombocythemia): Low-dose aspirin (50–100 mg/day) is recommended for 6 weeks postpartum in low-risk pregnancies 3
• Preeclampsia prevention: Most guidelines recommend stopping aspirin at delivery, though some extend to 35–37 weeks gestation or until delivery 3
• General postpartum period: The 6-week mark represents the end of the highest-risk period for pregnancy-related complications 3

If You Have Thrombophilia: LMWH, Not Aspirin

If you have inherited thrombophilia or prior VTE, the correct thromboprophylaxis is LMWH for 6 weeks postpartum, not aspirin alone 3:

• The American Society of Hematology recommends postpartum LMWH (prophylactic or intermediate-dose) for 6 weeks in women with thrombophilia and a family history of VTE 3
• For women with prior VTE and additional risk factors (including sickle cell disease), LMWH should be continued for the full 6-week postpartum period 4
• Aspirin is inadequate as sole VTE prophylaxis in high-risk patients 4

Recent Evidence on Postpartum Aspirin for VTE

A 2025 pilot randomized controlled trial (PARTUM) evaluated low-dose aspirin versus placebo in 257 postpartum women with moderate VTE risk factors 5. Key findings:

• No VTE events occurred in the aspirin group; one distal DVT occurred in the placebo group 5
• No major bleeding events occurred in either group 5
• The trial demonstrated feasibility but was underpowered to show definitive efficacy 5
• This evidence is preliminary and does not yet support routine aspirin use for postpartum VTE prevention in moderate-risk women 5

Breastfeeding Considerations

Low-dose aspirin is generally considered compatible with breastfeeding:

• Aspirin at 81 mg daily poses minimal risk during breastfeeding 1, 2
• However, if you require anticoagulation for thrombophilia, LMWH is preferred over aspirin and is safe during breastfeeding 3
• Warfarin can be considered postpartum during breastfeeding but is contraindicated during pregnancy 4

Clinical Decision Algorithm

Follow this approach:

1. If you were prescribed aspirin for preeclampsia prevention only: Stop at 6 weeks postpartum as prescribed 1, 2

2. If you have documented thrombophilia (Factor V Leiden, prothrombin gene mutation, protein C/S deficiency) without prior VTE:

   • No family history of VTE: Clinical surveillance only; stop aspirin at 6 weeks 3
   • Positive family history of VTE: Should have been on LMWH, not aspirin alone, for 6 weeks postpartum 3

3. If you have prior VTE or high-risk thrombophilia (homozygous Factor V Leiden, compound heterozygosity): Should be on LMWH for 6 weeks postpartum, not aspirin 3

4. If you have myeloproliferative neoplasm (polycythemia vera, essential thrombocythemia): Continue aspirin for the full 6 weeks postpartum as prescribed 3

Common Pitfalls to Avoid

• Do not confuse preeclampsia prophylaxis with VTE prophylaxis: Aspirin prevents preeclampsia but is inadequate for VTE prevention in high-risk patients 4, 1, 2
• Do not extend aspirin beyond 6 weeks postpartum without a specific indication: The highest-risk period for pregnancy-related complications ends at 6 weeks 3
• Do not rely on aspirin alone if you have documented thrombophilia with additional risk factors: LMWH is the evidence-based choice 3, 4

Discontinue the aspirin at 6 weeks as prescribed unless you have a specific ongoing indication (such as cardiovascular disease or myeloproliferative neoplasm) that requires long-term antiplatelet therapy beyond the postpartum period.