**6. Pharmacologic agents for prophylaxis of VTE**

The 2 most common agents used for prophylaxis of VTE are LMWH and Unfractionaded Heparin (UFH). Recent guidelines recommend LMWH (most recomended enoxaparin) as the first-line pharmacologic agent. Enoxaparin has a half-life of 4 to 6 hours and is eliminated by the kidney and it is not recommended in patients with significant impaired renal function but has the advantage of better bioavailability, longer half-life, more predictable anticoagulation effect, less bleeding risks, and less risk of heparin-induced thrombocytopenia and osteopenia [2–5, 17, 18].

The recommended dose of enoxaparin is typically 40 mg subcutaneously once a day. Obese women may require higher doses; some evidence supports the use of intermediate doses of enoxaparin (40 mg subcutaneously every 12 hours) for obese women or a weight-based prophylactic dose of 0.5 mg/kg subcutaneously every 12 hours of enoxaparin in morbidly obese women after cesarean delivery [2, 17].

UFH has a shorter half-life than LMWH of 60 to 90 minutes and is mostly cleared by the reticuloendothelial system, rendering it a good choice in women with renal disease. Recommended prophylactic dosages in the postpartum period is 5000 units subcutaneously every 8 to 12 hours [17].

Fondaparinux is a completely synthetic pentasaccharide heparin analog and the first of a new class of selective indirect antithrombin-dependent factor Xa inhibitors, which inhibits thrombin generation, has some benefit for thromboprophylaxis. Heparin-induced thrombocytopenia (HIT) is an extremely rare situations of fondaparinux in comparison with the UFH and LMWH, suggesting that fondaparinux is an alternative for the treatment of thrombosis associated with HIT [22]. In a small study in Japan short term fondaparinux (2,5 mg/day)appears to be an adequate and safe method for prevention of symptomatic VTE in women at risk after cesarean section [22, 23].

There are insufficient safety and efficacy data to recommend the use of new oral anticoagulants (e.g., apixaban, rivaroxaban, dabigatran) during the postpartum period [24, 25].
