Postpartum Aspirin for Blood Clots

Not yet recruiting at 2 trial locations

Overseen By Jill Baxter, BSc

Age: 18+

Sex: Female

Trial Phase: Phase 3

Sponsor: University of Calgary

Must not be taking: Anticoagulants, Aspirin

Disqualifiers: VTE history, Heart valve, APS, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Pivotal Trial (Near Approval) This treatment is in the last trial phase before FDA approval

Prior Safety Data This treatment has passed at least one previous human trial

Compensation: Varies

Number of Visits: 6

Duration: 6 weeks

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial tests whether taking low-dose aspirin daily for six weeks after childbirth is as effective as the usual care of injections in preventing blood clots in the legs or lungs. It targets postpartum individuals with certain risk factors for blood clots, such as a history of specific blood conditions or bed rest during pregnancy. Participants will either take aspirin or receive the standard injection treatment, low-molecular-weight heparin. The trial seeks individuals who have experienced preeclampsia, smoking during pregnancy, or an unplanned cesarean delivery. As a Phase 3 trial, it represents the final step before FDA approval, offering participants the opportunity to contribute to a potentially groundbreaking treatment.

Do I need to stop my current medications for the trial?

The trial information does not specify if you need to stop taking your current medications. It's best to discuss this with your doctor or the trial team.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Research has shown that low-dose aspirin is generally safe for preventing blood clots. It prevents platelets from sticking together. Studies indicate that aspirin can reduce the risk of clots by 10-20% in individuals at moderate to high risk. While safe for most, some studies mention possible side effects like stomach upset or a slight increase in bleeding risk.

Low-molecular-weight heparin, another blood thinner used to prevent clots, is usually well-tolerated but can sometimes cause bruising or irritation at the injection site.

Both treatments prevent blood clots, each with its own pros and cons. Considering the benefits and possible side effects is important when deciding to join a trial. ^{1 2 3 4 5}

Why do researchers think this study treatment might be promising for blood clots?

Researchers are excited about low-dose aspirin for preventing blood clots after childbirth because it offers a simpler and potentially safer alternative to traditional blood thinners like low-molecular-weight heparin. Unlike heparin, which requires injections and careful monitoring, aspirin is taken orally and is easier to administer. Aspirin’s anti-inflammatory properties could provide additional benefits, potentially improving recovery without the added complexity of managing injectable medications. This approach could make postpartum care more accessible and comfortable for new mothers.

What evidence suggests that this trial's treatments could be effective for preventing blood clots postpartum?

Research has shown that low-dose aspirin, which participants in this trial may receive, might help prevent blood clots after childbirth. One study found that aspirin could work as well as the usual blood thinner injections, such as low-molecular-weight heparin, another treatment option in this trial. Previous research suggests that using aspirin is not only possible but also necessary to gather more solid evidence. These studies support the idea that aspirin could be a simpler and more convenient option for new mothers at risk of these clots. ^{1 6 7 8 9}

Who Is on the Research Team?

Marc Rodger, MD

Principal Investigator

McGill University Health Centre/Research Institute of the McGill University Health Centre

Leslie Skeith, MD

Principal Investigator

University of Calgary

Are You a Good Fit for This Trial?

The PARTUM trial is for individuals who have recently given birth and are at risk of developing blood clots. Participants must be in the postpartum period and meet certain criteria that put them at higher risk for venous thromboembolism.

Inclusion Criteria

I have had a clot in a vein near the surface of my body.

I have a genetic condition that affects blood clotting.

Preeclampsia

Exclusion Criteria

I have received more than one dose of LMWH since giving birth.

More than 48 hours since delivery at the time of randomization

Unable or declined consent

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

Up to 48 hours post-delivery

Treatment

Participants receive either low-dose aspirin daily or low-molecular-weight heparin as per site-specific regimen for 6 weeks

6 weeks

Follow-up

Participants are monitored for safety and effectiveness after treatment

90 days

Follow-up at 6 weeks and 90 days post-randomization

What Are the Treatments Tested in This Trial?

Interventions

• Aspirin
• Low-molecular-weight heparin

Trial Overview

This study tests if taking low-dose aspirin daily for six weeks after giving birth can prevent blood clots as effectively as the standard treatment with low-molecular-weight heparin injections.

How Is the Trial Designed?

Group I: Aspirin Experimental Treatment 1 Intervention

Low-dose aspirin (75-100 mg) once daily for 6 weeks.

Group II: Low-molecular-weight heparin Active Control 1 Intervention

Site-specific low-molecular-weight heparin regimen as prescribed by the treating physician.

Aspirin is already approved in European Union, United States, Canada, China for the following indications:

Approved in European Union as Aspirin for:

• Pain relief
• Fever reduction
• Inflammation
• Cardiovascular disease prevention
• Preeclampsia prevention

Approved in United States as Aspirin for:

• Pain relief
• Fever reduction
• Inflammation
• Cardiovascular disease prevention
• Preeclampsia prevention

Approved in Canada as Aspirin for:

• Pain relief
• Fever reduction
• Inflammation
• Cardiovascular disease prevention
• Preeclampsia prevention

Approved in China as Aspirin for:

• Pain relief
• Fever reduction
• Inflammation
• Cardiovascular disease prevention

Who Is Running the Clinical Trial?

University of Calgary

Lead Sponsor

Trials

827

Recruited

902,000+

Canadian Institutes of Health Research (CIHR)

Collaborator

Trials

1,417

Recruited

26,550,000+

Published Research Related to This Trial

All six aspirin preparations tested effectively inhibited platelet aggregation to a similar extent, indicating their efficacy in reducing blood clotting, which is important for preventing heart attacks and strokes.

Ecotrin and S.R.A. showed delayed effects and inhibited platelet aggregation without measurable levels of aspirin in the bloodstream, suggesting a unique mechanism of action possibly involving acetylation of cyclooxygenase in the liver.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Aspirin kinetics and platelet aggregation in man. Siebert, DJ., Bochner, F., Imhoff, DM., et al.[2019]

Low-dose acetylsalicylic acid (ASA) significantly reduces the risk of pre-eclampsia and other pregnancy complications, with a notable reduction in rates of preterm birth and fetal growth restriction, based on a review of multiple studies.

ASA is generally safe for use during pregnancy, with rare side effects, primarily related to bleeding, making it a beneficial option for women at high risk of pregnancy-associated morbidity.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The Role of Acetylsalicylic Acid in the Prevention of Pre-Eclampsia, Fetal Growth Restriction, and Preterm Birth. Stubert, J., Hinz, B., Berger, R.[2023]

In a study involving healthy volunteers who took varying doses of acetylsalicylic acid (ASA) for one week, all doses significantly inhibited platelet function and increased bleeding times, indicating its effectiveness in thrombosis prophylaxis.

The research found that a daily dose of around 100 mg of ASA maximized the effects on platelet function and bleeding time, suggesting that higher doses do not provide additional benefits.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effects of different doses of some acetylsalicylic acid formulations on platelet function and bleeding times in healthy subjects. McLeod, LJ., Roberts, MS., Cossum, PA., et al.[2019]

In a study of 268 patients with acute cerebral ischemia treated with intravenous aspirin and low-dose heparin, the treatment was found to be safe, with only one case of symptomatic secondary intracerebral hemorrhage and a low incidence of gastrointestinal complications.

While the functional outcomes varied, with 28.3% of patients achieving a Rankin Scale score of 0 (no symptoms), the efficacy of this treatment needs further investigation in controlled trials to determine its effectiveness in acute stroke management.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Intravenously administered acetylsalicylic acid in combination with low-dose heparin in acute ischemic stroke: a safety analysis. Büttner, T., Hellwig, K., Müller, T., et al.[2013]

A study involving 46 healthy participants demonstrated that a novel 75 mg soft-gel capsule formulation of acetylsalicylic acid (ASA) is non-inferior to a marketed powder solution in reducing serum thromboxane B2 (TXB2), a marker for platelet aggregation.

Both formulations showed similar effectiveness in inhibiting TXB2, with no reported adverse events, suggesting that the soft-gel capsule could be a safe and effective alternative for preventing cardiovascular events.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Pharmacodynamics and pharmacokinetics of a novel, low-dose, soft-gel capsule of acetylsalicylic acid in comparison with an oral solution after single-dose administration to healthy volunteers: a phase I, two-way crossover study. Loprete, L., Leuratti, C., Scarsi, C., et al.[2021]

A quality improvement project in an academic OB/Gyn practice showed that implementing a standardized approach to aspirin (ASA) prescription significantly increased screening rates for preeclampsia risk from 47% to 99% among new obstetric patients.

Post-intervention, 79% of patients who screened positive received an ASA recommendation, demonstrating that the standardized process is effective and equitable, with no significant differences in recommendations based on race.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Leveraging quality improvement to promote health equity: standardization of prenatal aspirin recommendations. Gross, ME., Godecker, A., Hughes, A., et al.[2023]

Aspirin is considered safe for use during pregnancy at daily doses not exceeding 100mg and has been shown to effectively prevent pre-eclampsia and fetal growth restriction in high-risk patients.

However, aspirin has not demonstrated benefits for preventing vascular placental disease in low-risk patients or for unexplained recurrent miscarriages.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[Aspirin: Indications and use during pregnancy]. Belhomme, N., Doudnikoff, C., Polard, E., et al.[2018]

Citations

1.

ashpublications.org

ashpublications.org/bloodvth/article/doi/10.1016/j.bvth.2025.100106/547210/Low-molecular-weight-heparin-vs-aspirin-postpartum

Low-molecular-weight heparin vs aspirin postpartum (LEAP)

Key PointsPilot RCT shows feasibility of shorter LMWH + aspirin regimen vs 6-week LMWH for postpartum VTE prevention.

2.

clinicaltrials.gov

clinicaltrials.gov/study/NCT06494878?cond=Postpartum%20infections&aggFilters=status:not%20rec%20ava&viewType=Table&rank=5

Study Details | The PARTUM Trial: Postpartum Aspirin to ...

The goal of the PARTUM trial is to determine if taking low-dose aspirin daily for 6 weeks after delivery is similar (non-inferior) to usual care ...

3.

pubmed.ncbi.nlm.nih.gov

pubmed.ncbi.nlm.nih.gov/39827892/

Low-dose aspirin versus placebo in postpartum venous ...

A global postpartum thromboprophylaxis trial evaluating low-dose aspirin is possible and needed to provide high-quality data.

4.

arctic.ucalgary.ca

arctic.ucalgary.ca/news/ucalgary-researcher-testing-effectiveness-aspirin-preventing-postpartum-blood-clots

UCalgary researcher testing effectiveness of Aspirin in ...

The results, published in The Lancet: Haematology, showed that while ASA is a feasible option for preventing blood clots postpartum, a global ...

5.

sciencedirect.com

sciencedirect.com/science/article/pii/S0049384824002457

Examining postpartum anticoagulation practices

This study investigates postpartum thromboprophylaxis practices among clinicians managing high-risk patients.

6.

pmc.ncbi.nlm.nih.gov

pmc.ncbi.nlm.nih.gov/articles/PMC11194157/

Postpartum pharmacologic thromboprophylaxis and ...

Propensity score based on factors associated with postpartum prophylaxis: obesity, cesarean delivery, aspirin use, co-morbid conditions, pregnancy induced ...

7.

sciencedirect.com

sciencedirect.com/science/article/abs/pii/S2210778925000637

The timing of discontinuation of low-dose aspirin and ...

For patients at moderate to high risk, LDA has been reported to reduce these risks by 10–20 % [2,3]. Despite the general safety profile of LDA, some studies ...

8.

ashpublications.org

ashpublications.org/blood/article/140/Supplement%201/341/490681/LEAP-Pilot-Low-Molecular-Weight-Heparin-Vs-Aspirin

Low Molecular Weight Heparin Vs. Aspirin Postpartum | Blood

A 2014 Cochrane review concluded that there is insufficient evidence on which to base thromboprophylaxis in the pregnancy postpartum setting, ...

9.

withpower.com

withpower.com/trial/phase-3-thromboembolism-8-2024-1f159

Postpartum Aspirin for Blood Clots · Info for Participants

Research shows that aspirin (acetylsalicylic acid, ASA) is effective in preventing blood clots by inhibiting platelet function, which is important for clot ...