The efficacy for Vitamin K prophylaxis in the newborn is well establis
hed. Parenteral Vitamin K prophylaxis remains the norm for the newborn
infant in North America, though the recent controversy associating su
ch prophylaxis with the incidence of childhood cancer has given new im
petus to the consideration of oral prophylaxis. Oral preparations of v
itamin K for the newborn infant may be desirable and clinical trials a
re underway. The function and metabolism of vitamin K center around it
s ability to serve as cofactor for the action of Vitamin K dependent c
arboxylases present in most tissues. Hemorrhagic disease of the newbor
n is a well described deficiency of the vitamin and has several differ
ent presentations, the most serious of which occurs after two weeks of
age. On the other hand, vitamin K deficiency is probably not a factor
in the etiology of intraventricular hemorrhage in premature infants.
Vitamin K is not readily transported across the placenta, and its prod
uction by intestinal bacteria is not a significant source of the vitam
in for the newborn. The main source of vitamin K for the growing infan
t is dietary intake, though human milk from mothers on ordinary diets
is a very poor source of the vitamin. This probably accounts for the f
act that breast-fed infants are at the greatest risk for hemorrhagic d
isease. Assessment of coagulation factors is not a sensitive method to
assess Vitamin K deficiency or sufficiency. Newer methods for assessi
ng vitamin K status include direct assay of the vitamin concentration
in plasma or serum, as well as measurement of abnormal prothrombin ass
ociated with vitamin K deficiency (PIVKA-II). The specific antibody me
thod is the best technique for measuring abnormal prothrombin. Finally
, from a review of the most recent literature, it appears unlikely tha
t parenteral Vitamin K prophylaxis increases the risk of childhood can
cer.