Phytonadione is necessary for the body to synthesize coagulation factors. It is administered to the newborn to prevent bleeding disorders. It also promotes liver formation of the clotting factors II, VII, IX, and X. Newborns are vitamin K–deficient because the bowel does not have the bacteria necessary to synthesize fat-soluble vitamin K. The normal flora in the intestinal tract produces vitamin K. The newborn’s bowel does not support the normal production of vitamin K until bacteria adequately colonize it. The bowel becomes colonized by bacteria as food is ingested. Vitamin K does not promote the development of immunity or prevent the infant from becoming jaundiced.