Vitamin K is routinely given to all newborns to prevent Vitamin K Deficiency Bleeding (VKDB), a serious condition causing spontaneous bleeding in infants due to low levels of clotting factors. Newborns naturally have low vitamin K stores because it crosses the placenta poorly and gut bacteria, which produce vitamin K, are not yet established. A single intramuscular dose of vitamin K shortly after birth effectively reduces the risk of both early and late hemorrhagic disease in newborns. This prophylactic measure is a standard and critical practice in neonatal care worldwide.

Reference: Nelson Textbook of Pediatrics, Kliegman et al., 21st Edition.