Vitamin K Dose in Newborns
All healthy term newborns should receive a single intramuscular dose of 0.5 to 1 mg vitamin K1 within one hour of birth, as this is the most effective route for preventing vitamin K deficiency bleeding. 1, 2
Standard Prophylaxis for Term Infants
The intramuscular route is strongly preferred because it provides superior efficacy and reliability compared to oral administration 3, 4. The American Academy of Pediatrics and FDA-approved labeling both endorse this approach 1, 2.
Alternative Oral Regimens (Only if Parents Decline IM)
If parents refuse intramuscular administration after adequate counseling about increased bleeding risk, oral vitamin K may be given using one of these protocols 3, 4:
- Option 1: 2 mg orally at birth, repeated at 4-6 days, and again at 4-6 weeks 3
- Option 2: 2 mg orally at birth, then 1 mg weekly for 3 months 3
- Option 3: 3 doses of 2 mg orally at birth, 2-4 days, and 6-8 weeks 4, 5
Important caveat: Oral regimens are significantly less effective than IM administration for preventing late vitamin K deficiency bleeding, and success depends entirely on parental compliance 3, 4. If the infant vomits within 1 hour of oral administration, the dose should be repeated 3.
Special Populations Requiring Different Dosing
Preterm Infants on Parenteral Nutrition
- 10 μg/kg/day of vitamin K should be provided in parenteral nutrition solutions 6, 7, 8, 1
- This daily dosing differs from the single-dose prophylaxis used in term infants 6
High-Risk Infants
The following groups should receive IM or slow IV vitamin K (never oral) 9:
- Premature infants
- Infants with birth asphyxia or difficult delivery
- Those with hepatic disease or cholestasis 3
- Infants too unwell to take oral medications 3
- Infants whose mothers took anticonvulsants, anticoagulants, or antituberculosis drugs 7, 9
For infants of mothers on vitamin K-inhibiting medications, maternal prophylaxis (10-20 mg/day orally for 15-30 days before delivery) can prevent early bleeding, but the infant still requires neonatal prophylaxis with potential repeat dosing 9.
Treatment of Active Bleeding
For hemorrhagic disease of the newborn (treatment, not prophylaxis), give 1 mg vitamin K1 subcutaneously or intramuscularly 2. Higher doses may be necessary if the mother received oral anticoagulants 2. A prompt response with shortening of prothrombin time within 2-4 hours is diagnostic of vitamin K deficiency bleeding 7, 2.
Critical Pitfalls to Avoid
- Never use oral vitamin K in preterm infants or those with malabsorption disorders - these populations require parenteral administration 3, 9
- Document parental refusal if IM vitamin K is declined, as this creates significant medicolegal risk given the preventable nature of late vitamin K deficiency bleeding 3
- Avoid benzyl alcohol-containing diluents in newborns due to toxicity risk 2
- Do not exceed 1 mg per minute if IV administration is unavoidable 2