Current concepts and controversies in the use of vitamin K.

Vitamin K is a fat-soluble vitamin crucial to the production of many proteins involved with the coagulation process. It is integral in the synthesis of coagulants (factors II, VII, IX and X) and anticoagulants (proteins C and S). It is generally recognised that routine administration of vitamin K (phytomenadione) shortly after birth will prevent major neonatal morbidity and mortality related to haemorrhage. Vitamin K supplementation during pregnancy is also recommended if mothers are on anticonvulsant therapy or prolonged treatment with certain antibiotics. These medications, if ingested by pregnant women, predispose the neonate to a bleeding tendency caused by vitamin K deficiency. Vitamin K treatment of pregnant mothers before premature delivery has also been suggested to reduce the incidence of severe intracranial haemorrhage (ICH) in premature neonates. Although further studies are pending, the data to date do not support using antenatal vitamin K for preventing ICH.