Vitamin K Dosing for 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
Route of Administration
Intramuscular administration is strongly preferred over oral routes because it provides superior protection against all forms of vitamin K deficiency bleeding (VKDB), particularly late VKDB which can occur up to 6 months of age. 2, 3, 4
- The IM route ensures reliable absorption and compliance, eliminating concerns about regurgitation, vomiting, or missed follow-up doses that plague oral regimens. 2
- The FDA-approved dose is 0.5 to 1 mg given intramuscularly within one hour of birth. 1
Oral Alternative (Second-Line Only)
If parents decline IM vitamin K after adequate counseling about increased bleeding risk, oral administration may be offered as a compromise, though it is less effective: 2, 3, 4
Three acceptable oral regimens exist:
- Option 1: 2 mg at birth, repeated at 4-6 days, and again at 4-6 weeks 2
- Option 2: 2 mg at birth, then 1 mg weekly for 3 months 2
- Option 3: 3 doses of 2 mg each at birth, 2-4 weeks, and 6-8 weeks 3, 4
Critical Oral Regimen Caveats
- If the infant vomits or regurgitates within 1 hour of oral administration, repeat the dose. 2
- Compliance with multi-dose oral regimens is problematic—studies show up to 25% of infants miss recommended doses, placing them at increased risk. 5
- Parents must understand that oral prophylaxis carries higher VKDB risk than IM administration. 3, 4
Special Populations Requiring IM Route
The oral route is contraindicated and IM (or IV if necessary) must be used in: 2, 6
- Preterm infants
- Infants with cholestasis or malabsorption disorders
- Infants too ill to take oral medications
- Infants whose mothers took medications interfering with vitamin K metabolism (anticonvulsants, anticoagulants, antituberculosis drugs)
- Infants at high risk of hemorrhage (birth asphyxia, difficult delivery, neonatal disease)
For these high-risk infants, higher doses may be necessary if maternal anticoagulant exposure occurred, and repeated dosing should be individualized based on coagulation studies. 1, 6
Preterm Infants on Parenteral Nutrition
Preterm infants receiving parenteral nutrition require 10 μg/kg/day of vitamin K as part of their daily nutritional support, which differs from the prophylactic birth dose. 7, 8, 9
Documentation Requirements
The date, dose, and route of vitamin K administration must be documented in the medical record. 2
Parental refusal must be explicitly recorded due to the serious risk of late VKDB, which can present with catastrophic intracranial hemorrhage. 2