Willebrand's disease, the most frequent inborn coagulopathy, is defined as a deficiency in Willebrand's factor required for normal hemostasis as a mediator in platelet adhesion to the subendothelium and which also contributes to plasma coagulation pathway (by preserving the coagulating activity of factor VIII). Classically, Willebrand's disease improves somewhat during pregnancy. We followed 15 pregnancies in 12 patients with Willebrand's disease in an attempt to determine the best management strategy to reduce the risk of bleeding during delivery. This risk can be assessed on the basis of prior history of bleeding and the laboratory tests and reduced by administration of concentrated Willebrand's factor at 8 months gestation. In patients with type I disease, desmopressin is proposed as curative treatment during the post partum period. Antenatal diagnosis is possible in the most severe forms. Programmed delivery is recommended. Spinal analgesia is contraindicated.