Why is vitamin K administered to a newborn at birth?

Vitamin K is administered to newborns at birth primarily to prevent bleeding due to vitamin K deficiency. Newborns have low levels of vitamin K at birth because this vitamin does not readily cross the placenta during pregnancy, and breast milk contains only small amounts of it. Vitamin K is essential for the synthesis of certain proteins that are required for blood coagulation. Without adequate vitamin K, infants are at risk of developing serious bleeding conditions, such as hemorrhagic disease of the newborn, particularly within the first few days to weeks of life.

Administering vitamin K shortly after birth effectively ensures that the newborn has sufficient levels of this crucial vitamin to aid in normal blood clotting and reduce the risk of potentially life-threatening hemorrhages. This practice has become a standard and critical part of neonatal care.