The PARTUM Trial: Postpartum Aspirin to Reduce Thromboembolism Undue Morbidity

July 23, 2026 updated by: University of Calgary

The PARTUM (Postpartum Aspirin to Reduce Thromboembolism Undue Morbidity) Trial

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 low-molecular-weight heparin injections to prevent venous thromboembolism (VTE: blood clots in the legs or lungs) for postpartum individuals with VTE risk factors.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

The PARTUM trial design is a Prospective Randomized Open Blinded End-point (PROBE) non-inferiority trial. Participants with risk factors for venous thromboembolism (VTE) as defined by the inclusion criteria will be identified during pregnancy, labor and delivery, and up to 48 hours after delivery.

Eligible and consenting participants will be randomly assigned to one of two study arms: Low-dose aspirin (75-100mg according to country availability) daily for 42 days post-randomization, or a usual care site-specific low-molecular-weight-heparin (LMWH) regimen with the dose and duration of LMWH determined by the participant's healthcare provider.

Follow-up will occur at 6 weeks and 90 days post-randomization.

Study Type

Interventional

Enrollment (Estimated)

8805

Phase

  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • Belgium
      • Brussels, Belgium, 1020
        • Not yet recruiting
        • Association Hospitalière De Bruxelles Et De Schaerbeek - Centre Hospitalier Universitaire Brugmann
        • Contact:
        • Contact:
  • Canada
    • Alberta
      • Calgary, Alberta, Canada, T2N 2T9
        • Recruiting
        • Foothills Medical Centre
        • Contact:
        • Contact:
    • Ontario
      • Ottawa, Ontario, Canada, K1H 8L6
        • Not yet recruiting
        • The Ottawa Hospital - General Campus
        • Contact:
  • Denmark
    • Capital Region
      • Hvidovre, Capital Region, Denmark, 2650
        • Not yet recruiting
        • Hvidovre Hospital
        • Contact:
        • Contact:
        • Principal Investigator:
          • Charlotte Holm Bischof, MD, PhD
  • France
      • Nancy, France, 54000
        • Not yet recruiting
        • CHU de Nancy
        • Principal Investigator:
          • Olivier Morel, MD, PhD
        • Contact:
      • Paris, France, 75014
        • Not yet recruiting
        • APHP - Hôpital Port Royal
        • Contact:
        • Principal Investigator:
          • Aude Girault, MD, PhD
      • Saint-Etienne, France, 42055
      • Toulouse, France, 31059
        • Not yet recruiting
        • CHU de Toulouse
        • Contact:
        • Principal Investigator:
          • Paul Guerby, MD, PhD
  • Ireland
      • Dublin, Ireland, D01 P5W9
        • Not yet recruiting
        • Rotunda Hospital, RCSI Department of Obstetrics and Gynaecology
        • Contact:
          • Jennifer Donnelly, Consultant Obstetrician/MFM, MD
          • Phone Number: 0876497966
          • Email: jdonnelly@rotunda.ie
        • Contact:
      • Dublin, Ireland, D08XW7X
        • Not yet recruiting
        • UCD Centre for Human Reproduction, The Coombe Hospital
        • Contact:
          • Amy O'Higgins, Associate Professor of Obstetrics & Gynaecology
          • Phone Number: 4887 +353 1 4085200
          • Email: amy.ohiggins@ucd.ie
        • Contact:
  • Netherlands
      • Amsterdam, Netherlands, 1105AZ
  • Poland

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • ONE (or more) First Order Criterion:

    1. Known inherited thrombophilia diagnosed prior to enrolment, regardless of family history of VTE:

      i. Heterozygous factor V Leiden, or ii. Heterozygous prothrombin gene variant, or iii. Protein C deficiency, or iv. Protein S deficiency, and/or

    2. Antepartum immobilization for ≥7 days. Immobilization is defined as bed rest with 90% of waking hours spent in bed at any time during the antepartum period AND/OR

TWO (or more) Second Order Criteria:

  1. Pre-pregnancy BMI ≥30 kg/m²
  2. Smoking in the current pregnancy or within 3 months prior to pregnancy
  3. Previous clinical history of superficial vein thrombosis
  4. Preeclampsia
  5. Current pregnancy ending in stillbirth (pregnancy loss >20 weeks gestation)
  6. Unplanned cesarean delivery (unplanned = not a scheduled cesarean delivery)
  7. Small-for-gestational-age infant at time of delivery (<3rd percentile adjusted for gestational age and sex)
  8. Peripartum or postpartum infection (symptoms/signs of infection and documented fever and laboratory evidence of infection with positive blood cultures or an elevated white blood cell count based on local laboratory cutoffs)
  9. Postpartum hemorrhage (≥1000 mL of blood loss, regardless of delivery mode)

Exclusion Criteria:

  1. More than 48 hours since delivery at the time of randomization
  2. Received more than 1 dose of LMWH since delivery

  3. Need for postpartum LMWH prophylaxis or systemic anticoagulation as judged by their physician and/or local investigator. May include but is not limited to:

    1. Documented history of provoked or unprovoked VTE
    2. Mechanical heart valve(s)
    3. Known antiphospholipid syndrome (APS)
    4. Known high-risk inherited thrombophilia i) Antithrombin deficiency, or ii) Homozygous factor V Leiden, or iii) Homozygous prothrombin gene mutation, or iv) More than 1 thrombophilia: any combination of 2 or more: factor V Leiden, prothrombin gene mutation, protein C deficiency, protein S deficiency

  4. Need for postpartum ASA as judged by their physician and/or local investigator. May include but is not limited to:

    1. Documented history of myocardial infarction
    2. Documented history of ischemic stroke or transient ischemic attack (TIA)
  5. Active bleeding, excluding normal vaginal bleeding, at the time of randomization
  6. Known medical condition as judged by their physician and/or local investigator to be a contraindication to ASA or LMWH including known ASA or LMWH allergy
  7. <18 years of age
  8. Unable or declined consent

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Aspirin
Low-dose aspirin (75-100 mg) once daily for 6 weeks.
Drug: Aspirin
75-100 mg taken once daily by mouth.
Active Comparator: Low-molecular-weight heparin
Site-specific low-molecular-weight heparin regimen as prescribed by the treating physician.
Drug: Low-molecular-weight heparin
Low-molecular-weight heparin injections daily as prescribed by the treating physician.
Other Names:
  • Dalteparin, Enoxaparin, Nadroparin, Tinzaparin

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Symptomatic VTE
Time Frame: 6 weeks
Proximal lower or upper extremity DVT, PE involving segmental or higher arteries or multiple subsegmental arteries, and unusual site [non-limb] venous thromboembolism
6 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Late symptomatic VTE
Time Frame: 90 days
Proximal lower or upper extremity DVT, PE involving segmental or higher arteries or multiple subsegmental arteries, and unusual site [non-limb] venous thromboembolism
90 days
Superficial vein thrombosis
Time Frame: At 6 weeks and at 90 days
A non-compressible vein segment on ultrasound that involves the superficial veins in the lower or upper extremity
At 6 weeks and at 90 days
Distal deep vein thrombosis
Time Frame: At 6 weeks and at 90 days
A non-compressible vein segment on ultrasound involving the deep veins that is distal to the popliteal vein in the lower extremity, or distal to the axillary vein in the upper extremity
At 6 weeks and at 90 days
Single subsegmental pulmonary embolism (SSPE)
Time Frame: At 6 weeks and at 90 days
Intraluminal filling defect that involves one subsegmental artery only
At 6 weeks and at 90 days
Major bleeding
Time Frame: At 6 weeks and at 90 days
Based on the ISTH definition
At 6 weeks and at 90 days
Clinically relevant non-major bleeding
Time Frame: At 6 weeks and at 90 days
Based on the ISTH definition
At 6 weeks and at 90 days
Wound hematoma requiring intervention
Time Frame: At 6 weeks and at 90 days
Requiring intervention such as hematoma evacuation or wound packing
At 6 weeks and at 90 days
Symptomatic arterial thromboembolism
Time Frame: At 6 weeks and at 90 days
Ischemic stroke/transient ischemic attack, myocardial infarction, or peripheral arterial embolism
At 6 weeks and at 90 days
Postpartum preeclampsia
Time Frame: At 6 weeks and at 90 days
New preeclampsia presenting in the postpartum period
At 6 weeks and at 90 days
Heparin-induced thrombocytopenia
Time Frame: At 6 weeks and at 90 days
According to a priori categories of definite or possible HIT.
At 6 weeks and at 90 days
All-cause mortality
Time Frame: At 6 weeks and at 90 days
At 6 weeks and at 90 days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Calgary

Collaborators

Canadian Institutes of Health Research (CIHR)
European Clinical Research Infrastructure Network

Investigators

  • Principal Investigator: Marc Rodger, MD, McGill University Health Centre/Research Institute of the McGill University Health Centre
  • Principal Investigator: Leslie Skeith, MD, University of Calgary

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

June 4, 2026

Primary Completion (Estimated)

September 1, 2030

Study Completion (Estimated)

December 1, 2030

Study Registration Dates

First Submitted

June 12, 2024

First Submitted That Met QC Criteria

July 2, 2024

First Posted (Actual)

July 10, 2024

Study Record Updates

Last Update Posted (Actual)

July 27, 2026

Last Update Submitted That Met QC Criteria

July 23, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • REB24-0317

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Data will be shared upon request.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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