Why do newborns receive a vitamin K (Vit K) shot?

Why Newborns Receive Vitamin K Shots

Newborns receive vitamin K shots to prevent potentially life-threatening vitamin K deficiency bleeding (VKDB), which can cause severe complications including intracranial hemorrhage, as newborns are physiologically deficient in vitamin K at birth. 1

Understanding Vitamin K Deficiency in Newborns

Newborns are particularly vulnerable to vitamin K deficiency for several reasons:

• Poor placental transfer of vitamin K during pregnancy
• Low vitamin K content in breast milk
• Immature gut flora that limits vitamin K synthesis
• Immature liver function that affects clotting factor production 2

Vitamin K is essential for the synthesis of coagulation factors II, VII, IX, and X, as well as proteins C and S, which are critical for normal blood clotting. Without adequate vitamin K, newborns are at risk for bleeding complications 3.

Types of Vitamin K Deficiency Bleeding

VKDB is classified into three categories based on timing:

1. Early VKDB: Occurs within 24 hours after birth
2. Classic VKDB: Occurs within the first week of life
3. Late VKDB: Occurs between 2 weeks and 6 months of age 2

Late VKDB is particularly concerning as it often presents with intracranial hemorrhage, which can be fatal or cause permanent neurological damage 4.

Vitamin K Administration Recommendations

The current evidence strongly supports vitamin K prophylaxis for all newborns. The preferred options include:

• Intramuscular (IM) injection: 1 mg vitamin K1 at birth (preferred method)
• Oral administration: Either 3 doses of 2 mg vitamin K1 (at birth, 4-6 days, and 4-6 weeks) or 2 mg at birth followed by weekly 1 mg doses for 3 months 1

The intramuscular route is considered more reliable and effective, particularly for preventing late VKDB 1.

Special Considerations

Certain newborns are at higher risk and require special attention:

• Exclusively breastfed infants (breast milk contains less vitamin K than formula)
• Infants with cholestasis or other conditions affecting fat absorption
• Premature infants
• Infants whose mothers took medications that interfere with vitamin K metabolism (e.g., anticoagulants, anticonvulsants) 3, 5

For these high-risk infants, the intramuscular route is strongly preferred over oral administration 5.

Consequences of Omitting Vitamin K Prophylaxis

Refusal or omission of vitamin K prophylaxis puts newborns at significant risk:

• Increased incidence of VKDB, particularly late-onset bleeding
• Risk of intracranial hemorrhage requiring neurosurgical intervention
• Potential for permanent neurological damage or death 4

A concerning trend of parental refusal of vitamin K prophylaxis has led to an increase in preventable cases of VKDB 4, 6.

Common Pitfalls and Caveats

• Oral administration compliance: Success depends on strict adherence to the dosing schedule, which may be challenging for parents 1
• Vomiting after oral dose: If the infant vomits within 1 hour of administration, the dose should be repeated 1
• False sense of security: Some infants may have unrecognized risk factors for VKDB that only become apparent after bleeding occurs 6
• Documentation: The date, dose, and mode of administration should be carefully documented, especially in cases of parental refusal 1

Vitamin K prophylaxis is a simple, safe, and effective intervention that prevents a potentially devastating condition in newborns. The intramuscular route remains the gold standard for reliability and effectiveness in preventing all forms of VKDB.