What happens if my girlfriend has von willebrand disease and i don't what's the chances of our children getting it?

50% in most cases: an overwhelming majority of von Willebrand Disease (VWD) is dominant, meaning that if you carry one gene, you have VWD. Supposing that your girl friend has one VWD on one chromosone, and the other is normal, the chance of her passing that VWD gene to your offspring would be 50%. Most patients with VWD have type 1 disease which is fully compatible with normal life span.