Comparison of Low and Intermediate Dose Low-molecular-weight Heparin to Prevent Recurrent Venous Thromboembolism in Pregnancy

Low-molecular-weight Heparin to Prevent Recurrent VTE in Pregnancy: a Randomized Controlled Trial of Two Doses

This is a randomized-controlled open-label trial comparing two different doses of low-molecular-weight heparin (LMWH) in pregnant patients with a history of previous venous thromboembolism (VTE). Both doses are recommended doses in the 2012 guidelines of the American College of Chest Physicians (ACCP), but it is not known which dose is more efficacious in preventing recurrent venous thromboembolism in pregnancy.

Patients enter the study and will be randomized as soon as a home test confirms pregnancy. LMWH will be administered until 6 weeks postpartum. Follow-up will continue until 3 months postpartum. Patients will be recruited by their treating physician, either an obstetrician or internist.

Inclusion Criteria:

• Age: 18 years or older, and;
• Pregnancy confirmed by urinary pregnancy test, and;
• Gestational age < 14 weeks, and;
• Previous objectively confirmed VTE, either unprovoked, in the presence of use of oral contraceptives or estrogen/progestagen use, or related to pregnancy or the postpartum period, or minor risk factors (e.g. long distance travel, minor trauma).

Exclusion Criteria:

• Previous VTE related to a major provoking risk factor (e.g. surgery, major trauma or plaster cast immobilisation in the 3 months prior to VTE) as the sole risk factor, or;
• Indication for treatment with therapeutic dose anticoagulant therapy (e.g. treatment of acute VTE; permanent use of therapeutic anticoagulants outside of pregnancy), or;
• Inability to provide informed consent, or;
• Any contraindication listed in the local labelling of LMWH.