Pilot PARTUM Trial: Postpartum Aspirin to Reduce Thromboembolism Undue Morbidity (PARTUM)

Inclusion Criteria: Study inclusion criteria includes one (or more) first order criterion or two (or more) second order criteria. A patient is still eligible if they have multiple criteria met, at the discretion of the local investigator.

ONE (or more) First Order Criteria:

1. Known inherited thrombophilia diagnosed prior to enrolment:

   i) Heterozygous factor V Leiden, OR ii) Heterozygous prothrombin gene variant, OR iii) Protein C deficiency, OR iv) Protein S deficiency

2. Immobilization (90% of waking hours spent in bed) for ≥7 days anytime during the antepartum period

TWO (or more) Second Order Criteria:

1. Postpartum infection
2. Postpartum hemorrhage (>1000 mL of blood loss, regardless of delivery mode)
3. Pre-pregnancy BMI ≥30 kg/m2
4. Emergency or unplanned cesarean delivery
5. Smoking ≥5 cigarettes/day before pregnancy
6. Pre-eclampsia
7. Current pregnancy ending in stillbirth (pregnancy loss >20 weeks gestation)
8. Small-for-gestational-age infant (<3rd percentile adjusted for gestational age and sex).
9. Previous history of superficial vein thrombosis

Exclusion Criteria:

1. More than 48 hours since delivery
2. Received more than 2 doses of low-molecular-weight heparin (LMWH) since delivery

3. Need for postpartum LMWH prophylaxis or systemic anticoagulation as judged by the 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
   4. Known high-risk inherited thrombophilia i) Antithrombin deficiency; ii) Homozygous factor V Leiden; iii) Homozygous prothrombin gene mutation; iv) Compound heterozygosity factor V Leiden and prothrombin gene mutation; v) More than one inherited thrombophilia

4. Need for postpartum aspirin as judged by the 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. Contraindication to aspirin including:

   1. History of known aspirin allergy
   2. Documented history of a gastrointestinal ulcer
   3. Known platelet count <50 x 109/L at any time during the current pregnancy or postpartum
   4. Active bleeding at any site, excluding normal vaginal bleeding, at the time of randomization
   5. Most recent known hemoglobin ≤70 g/L documented during the current pregnancy or postpartum
   6. Known severe hypertension (SBP >200mm/hg and/or DBP >120mm/hg) during the current pregnancy or postpartum
6. <18 years of age
7. Unable or refused consent