Maternal Newborn

Newborns begin life with limited vitamin K availability. Placental transfer is limited, intestinal bacteria have not yet established a meaningful contribution to vitamin K production, and human milk provides relatively little vitamin K. The liver therefore has less of the cofactor needed to produce clotting factors II, VII, IX, and X. The clinical consequence is vitamin K deficiency bleeding. An infant may initially feed, breathe, and appear well while clot formation is impaired. Bleeding can be visible at a puncture site or umbilicus, but it may also be internal and difficult to detect until the infant becomes pale, lethargic, apneic, or neurologically abnormal. Prophylaxis supplies vitamin K before this preventable deficiency becomes clinically dangerous. This injection prevents deficiency-related bleeding; it does not explain every bleeding presentation or treat a separate cause such as thrombocytopenia, trauma, infection, or a congenital bleeding disorder. A newborn who is bleeding still requires prompt assessment, even when vitamin K was documented.