Vitamin K Is Necessary for Newborns

Fat-soluble vitamin K is a critical part of the activation of coagulation factors II (prothrombin), VII, IX, and X. Compared with adults and older children, newborns have much lower levels of vitamin K: approximately 40% to 60% of normal adult values, which are not typically reached until approximately 6 months of age. This phenomenon is multifactorial, driven in part by low transplacental transfer of vitamin K, low levels of vitamin K excreted in human milk, and a physiologic delay in the acquisition of gut microflora that synthesize vitamin K, which is actually active in several forms. Vitamin K₁, or phylloquinone, is present in green leafy vegetables and is the most common source of vitamin K for humans. Vitamin K₂, or menaquinone, is synthesized by bacteria and is found in some animal and fermented products.

Vitamin K was first discovered in 1929 by Henrik Dam, who observed hemorrhages in chicks fed fat-free diets. Edward Doisy identified the structure and forms of vitamin K in the 1940s, and both men received the Nobel Prize for their collective work on vitamin K in 1943. Because of its critical role in hemostasis, vitamin K deficiency can cause bleeding in the infant. Vitamin K deficiency bleeding (VKDB) was first described in the 1930s shortly after the compound’s discovery, with the first infants given vitamin K to treat clinical bleeding later that decade. Swedish researcher Jörgen Lehmann compared the use of oral and intramuscular (IM) vitamin K in the …