Vitamin K prophylaxis for preterm infants.

Vitamin K is the most common 'drug' administered to babies born in the western world. For many decades vitamin K prophylaxis has been a routine treatment at birth for preterm infants. Despite universal use in preterm infants, very little work has been done to date to refine vitamin K dosage in this population or to assess vitamin K status after prophylaxis. Current regimens of prophylaxis used for preterm infants vary widely in terms of dose, route of administration, and formulation used.