Inclusion Criteria:One or more of the following

• Previous preeclampsia
• Previous unexplained intra-uterine growth restriction

• Previous recurrent miscarriage:

  • 3 or more unexplained miscarriage at less than 10 weeks gestation
  • 2 or more unexplained fetal loss between 10 and 16 weeks gestation
  • 1 or more unexplained fetal loss at or greater than 16 weeks gestation
• Previous abruptio placenta

• Women with one or more of the following thrombotic events:

  • Previous documented secondary proximal VTE
  • Previous documented calf-vein thrombosis (idiopathic or secondary)
  • Previous superficial phlebitis
• First degree relative with symptomatic thrombophilia
• Pregnancy - > 4weeks gestation and < 20 weeks gestation
• Thrombophilia:
• Two abnormal tests, and no normal tests
• Protein S
• Protein C
• Antithrombin
• Two positive tests
• Anticardiolipin IgM (>30 U/ml)
• Anticardiolipin IgG (>30 U/ml)
• Anti-b2 glycoprotein IgG (>20 U/ml)
• Anti-b2 glycoprotein IgM (>20 U/ml)
• Lupus anticoagulant
• One positive test
• Factor V Leiden (heterozygous or homozygous)
• Prothrombin gene defect (heterozygous or homozygous)

Exclusion Criteria:

• Less than 4 weeks gestation
• Greater than 19+6 weeks gestation

• Contraindication to heparin therapy

  • History of heparin induced thrombocytopenia
  • Platelet count less than 100,000 109/L
  • History of osteoporosis or steroid use
  • Actively bleeding
  • Documented peptic ulcer within 6 weeks
  • Heparin, bisulfite or fish allergy
  • Severe hypertension (SBP >200mmhg and/or DBP >120mmHg)
  • Serum creatinine greater than 80 umol/L (1.3mg/dl) and an abnormal 24 hour urine creatine clearance (<30ml/min)
  • Severe hepatic failure (INR >1.8)
• Geographic inaccessibility

• Need for anticoagulants, discretion of the investigator such as but not limited to:

  • Recurrent fetal loss and phospholipid antibody syndrome

  • Prior idiopathic proximal VTE:

    • History of idiopathic DVT or PE treated with anticoagulants (> 1 month of heparin or warfarin) or IVC interruption;
    • Idiopathic is a VTE occurring outside all of the following periods: antepartum, postpartum, oral contraceptive use, surgery, immobilaztion, cast, and malignancy
  • Mechanical heart valve
• Legal lower age limitations (country specific)
• Prior participation in TIPPS
• Unable/unwilling to provide informed consent