DDAVP can be used antenatally to raise factor VIII and von Willebrand factor plasma levels two‐ to sixfold during pregnancy in women with haemophilia A and type 1 von Willebrand disease;6, 10, 19, 26, 27, 28 it has a category B2 safety warning for use in pregnancy in Australia29 but does not cross the placenta at detectable levels.28, 30 with peak levels at 30–90 minutes after infusion, although there is considerable inter‐individual variation.27, 28, 30. The gene discussed is VWF; the disease is hemophilia A.