Minor Transplacental Passage of Fondaparinux in Vivo

To the Editor: Low-molecular-weight heparin remains the anticoagulant of choice for pregnant women with previous thromboembolic events. Fondaparinux (Arixtra, Sanofi-Synthelabo) is a chemically synthesized derivative of the natural pentasaccharide sequence that mediates the interaction of heparin with antithrombin.1 It has been recommended for prophylaxis against thromboembolism after hip or knee surgery.2,3 My colleagues and I have treated five pregnant patients in whom anticoagulant therapy was indicated and who had severe cutaneous allergic reactions to low-molecular-weight heparin with fondaparinux at a dose of 2.5 mg per day. No allergic reactions at injection sites, thromboembolic events, or abnormal bleeding was observed. . . .