A 34-year-old primigravida who had undergone thrombectomy for deep venous thrombosis (DVT) in her leg and exhibited low protein S activity, indicating predisposition to thrombosis, developed DVT of the leg. No pulmonary embolism was detected. After anticoagulant therapy with unfractionated heparin was discontinued because of liver dysfunction, danaparoid treatment was administered in hospital. The patient had a normal delivery after 39 weeks' gestation with no recurrence of thrombosis. During her second pregnancy four years later, she gave herself fondaparinux injections. She delivered normally after 38 weeks' gestation without experiencing DVT. Fondaparinux may be a useful anticoagulant for heparin-intolerant pregnant women.