Administration of oral Vitamin K is less effective than an injection, due to erratic absorption from the gastrointestinal tract and has to be given weekly until a baby is three months of age.

a baby is still at risk for a vitamin K deficiency without an injection after birth. According to the American Academy of ...

Carter. The American Academy of Pediatrics began recommending Vitamin K at birth in 1961. Dr. Carter says without this injection newborns are susceptible to Hemorrhagic Disease of the Newborn or ...