Why is vitamin K (Vit K) administered to newborns at birth?

Why Vitamin K is Given at Birth

All newborns should receive vitamin K prophylaxis at birth—preferably as a single intramuscular dose of 0.5 to 1.0 mg within one hour of delivery—to prevent life-threatening vitamin K deficiency bleeding (VKDB). 1, 2, 3

The Physiologic Problem

Newborns are uniquely vulnerable to bleeding disorders because:

• They have physiologically low plasma levels of vitamin K-dependent coagulation factors (factors II, VII, IX, and X) compared to adults 4
• Breast milk contains very low concentrations of vitamin K, making exclusively breastfed infants particularly susceptible to deficiency 4, 2
• Inadequate prenatal storage leaves newborns with insufficient vitamin K reserves at birth 5

Types of Vitamin K Deficiency Bleeding

Without prophylaxis, infants can develop three forms of VKDB 6, 7:

• Early VKDB: Occurs within 24 hours of birth
• Classic VKDB: Occurs between days 2-7 of life
• Late VKDB: Occurs between 2 weeks and 6 months, often presenting with catastrophic intracranial hemorrhage 8

The Gold Standard: Intramuscular Administration

The single IM dose of 0.5-1.0 mg at birth is the most effective and reliable method to prevent all forms of VKDB 2, 5:

• Must be administered within one hour of birth 1, 2
• This route is superior to oral administration for preventing late VKDB 6, 7
• The American Academy of Pediatrics specifically recommends this as the preferred approach 1, 3

Alternative: Oral Administration (Less Effective)

If parents refuse IM administration, oral regimens can be offered but with clear documentation of increased risk 2, 6:

• Option 1: 2 mg at birth, 2 mg at 4-6 days, and 2 mg at 4-6 weeks 2, 6
• Option 2: 2 mg at birth, then weekly 1 mg doses for 3 months (12 weeks total) 2
• Critical limitation: Oral prophylaxis is less effective than IM for preventing late VKDB 6, 7
• If the infant vomits or regurgitates within 1 hour, the oral dose should be repeated 6

Populations Where Oral Route is NOT Appropriate

Oral vitamin K should never be used in 6:

• Preterm infants
• Newborns with cholestasis or impaired intestinal absorption
• Infants too unwell to take oral medication
• Infants whose mothers took medications interfering with vitamin K metabolism (anticonvulsants, anticoagulants, antituberculosis drugs) 4

Real-World Consequences of Omission

The consequences of refusing or omitting vitamin K prophylaxis can be devastating 8:

• A case series documented seven infants with vitamin K deficiency over eight months, all of whom had not received prophylaxis at birth 8
• Four of seven infants developed intracranial hemorrhage, with two requiring urgent neurosurgery 8
• Mean age at presentation was 10.3 weeks, demonstrating the delayed nature of late VKDB 8
• Even a single case report showed an exclusively breastfed infant dying from intracranial hemorrhage despite receiving an inadequate dose (0.2 mg instead of 0.5-1.0 mg) 9

Safety Profile

Vitamin K1 (phylloquinone) is considered safe with no known adverse effects or toxicity concerns 2:

• While historical concerns about childhood leukemia were raised, an increased risk of solid tumors can be definitively excluded 7
• A low potential risk of lymphoblastic leukemia cannot be completely ruled out, but this has not changed guideline recommendations given the life-threatening nature of VKDB 7

Diagnostic Confirmation

A prompt response (shortening of prothrombin time within 2-4 hours) following vitamin K administration is diagnostic of VKDB 4, 2, 3:

• This rapid correction distinguishes VKDB from other coagulation disorders 3
• Failure to respond indicates another diagnosis and warrants further investigation 3

Documentation Requirements

The date, dose, and mode of administration must be documented 6:

• Parental refusal after adequate information should be specifically recorded due to the risk of late VKDB 6
• This documentation is critical for continuity of care and medicolegal purposes 6