We report a patient who presented with a left proximal deep vein thrombosis at 25 + 5 weeks gestation. She developed a severe urticarial rash 3 weeks following initiation of therapy with Enoxaparin. The patient was heterozygous for the factor V Leiden mutation. She was treated with subcutaneous twice-daily danaparoid (Orgaran) for the remainder of the pregnancy, achieving anti-Xa levels in the therapeutic range 0.5-1.0 IU/ml. Delivery was at term by caesarean section 2 days after spontaneous rupture of membranes and failure to progress in labour. Danaparoid was withheld during this time. Danaparoid was restarted 3 h post delivery and the patient anticoagulated with warfarin in the post-partum period. There was no recurrence of thrombosis or bleeding events during therapy with danaparoid. No anti-Xa activity was demonstrated in breast milk.