Vitamin K is required by the liver for synthesis of many clotting factors and building of bones. So, it's deficiency will result in abnormal clotting and excessive bleeding.
Hemorrhagic disease of newborn -
Premature babies have limited stores of vitamin K, which may result in abnormal bleeding in babies during first few months of life. This bleeding may be minor but prolonged bleeding example into the brain may be fatal.
Deficiency in adults -
Vitamin K is absorbed in colon with the help of bile salts. Vitamin K deficiency may occur when you have liver disease. It may also occur during treatment with drugs that sterilize the bowel. Vitamin K deficiency in adults may contribute to abnormal bleeding, poor bone development, osteoporosis and increased rise of a cardio-vesicular disease. Generally, injections are given to people before their any minor or major surgery.