Why is vitamin K (Vitamin K1, phylloquinone) injection recommended for newborns?

Rationale for Vitamin K Injection in Newborns

Vitamin K injection is recommended for all newborns to prevent potentially life-threatening vitamin K deficiency bleeding (VKDB), particularly intracranial hemorrhage, which can lead to significant morbidity and mortality.

Why Vitamin K Prophylaxis is Necessary

Newborns are physiologically vitamin K deficient for several important reasons:

• Vitamin K-dependent coagulation factors (II, VII, IX, X) are naturally low in newborns 1
• Limited placental transfer of vitamin K during pregnancy
• Breast milk contains low concentrations of vitamin K 2
• Newborns have sterile intestines at birth and lack the gut bacteria needed to synthesize vitamin K

Without prophylaxis, this deficiency can lead to three types of VKDB:

1. Early VKDB: Within 24 hours of birth
2. Classic VKDB: Days 1-7 of life
3. Late VKDB: Week 2-6 months of life, often presenting with intracranial hemorrhage

Evidence Supporting Intramuscular Administration

The American Academy of Pediatrics recommends administering 0.5-1 mg of vitamin K1 (phylloquinone) intramuscularly within the first hour after birth 1. This recommendation is based on strong evidence showing:

• IM administration is more effective than oral administration in preventing all forms of VKDB, particularly late VKDB 3
• A single IM dose provides protection for several months
• IM administration ensures complete delivery of the dose (no concerns about vomiting, regurgitation, or poor absorption)

Special Considerations

Certain newborns are at higher risk of VKDB and require particular attention:

• Premature infants
• Infants with perinatal asphyxia or difficult delivery
• Infants with delayed feeding
• Infants with known liver disease or cholestasis
• Infants whose mothers took medications that interfere with vitamin K metabolism 1, 4

For these high-risk infants, the intramuscular route is strongly preferred over oral administration 4.

Oral vs. Intramuscular Administration

While some parents may request oral vitamin K administration, healthcare providers should clearly explain the limitations:

• Oral administration requires multiple doses (typically 2-3 doses) to provide adequate protection 3
• Compliance with follow-up doses is critical but variable
• Oral administration is less reliable for preventing late VKDB, which often causes intracranial hemorrhage 5
• Oral administration is contraindicated in preterm infants, infants with cholestasis, impaired intestinal absorption, or those too unwell to take oral medication 3

Common Pitfalls to Avoid

1. Assuming all newborns are at equal risk: Even apparently healthy newborns may have unrecognized risk factors for VKDB 5
2. Relying on a single oral dose: This provides inadequate protection against late VKDB
3. Failing to document administration: The date, dose, and route of vitamin K administration should always be documented 3
4. Inadequate parental education: Parents who refuse vitamin K should be thoroughly informed about the risks of VKDB, particularly intracranial hemorrhage

Conclusion

The Canadian Paediatric Society and College of Family Physicians of Canada recommend routine IM administration of a single dose of vitamin K (0.5-1 mg) to all newborns 6. This approach provides the most reliable protection against all forms of VKDB, particularly the late form which can cause devastating intracranial hemorrhage.