The effect of vitamin K1 prophylaxis was assessed in 507,850 babies born in Denmark from November 1992 to June 2000. Of these, 78% (about 396,000) received oral and 22% received intramuscular (IM) prophylaxis. The oral regimen used was 2 mg given at birth, followed by 1 mg once a week until age 3 months, as long as the babies were more than 50% breast-fed. Those given IM prophylaxis also received weekly oral vitamin K, as described above. Compliance was good, with 94% of the infants completing the course of treatment. No case of vitamin K-deficiency bleeding (VKDB) occurred in either group.

Comment: Oral vitamin K prophylaxis given once at birth was used in many European countries during the past two decades, but was abandoned because of unsatisfactory protection from late VKDB. In Denmark, weekly oral prophylaxis was practiced from November 1992 to June 2000, at which time Roche withdrew the only licensed vitamin K1 preparation (Konakion®) from the market, without any explanation. The current retrospective study demonstrates that weekly oral vitamin K supplementation during the first three months of life is an effective method of preventing hemorrhagic disease during infancy. In contrast, during the time when oral vitamin K prophylaxis consisted of a single dose at birth, the incidence of late VKDB in Denmark was 4.5 per 100,000.

Giving IM injections to neonates can cause pain and also carries a small risk of infection, hematoma, and neuronal damage. Moreover, IM administration of vitamin K1 is unphysiologic, resulting in transient plasma vitamin K levels 1,000 times greater than the normal adult values. Consequently, oral vitamin K prophylaxis is preferable in cases where it is expected to be effective. IM prophylaxis may be preferable for high-risk infants; i.e., those with gestational age less than 33 weeks, a history of difficult delivery or asphyxia requiring resuscitation, or a mother who is using anticonvulsant medication. Vitamin K-enriched formulas (usually containing 50 mcg of vitamin K per liter) provide good protection against late VKDB, since the disease is seen almost exclusively in breast-fed infants.

Hansen KN, et al. Weekly oral vitamin K prophylaxis in Denmark. Acta Paediatr 2003;92:802-805.