Can we administer Vitamin K (Vit K) and Hepatitis B (Hep B) vaccines to a 31-week-old newborn?

Vitamin K and Hepatitis B Vaccination in a 31-Week Preterm Newborn

Yes, administer Vitamin K immediately after birth, but delay the Hepatitis B vaccine until hospital discharge or 1 month of age if the mother is HBsAg-negative.

Vitamin K Administration

Vitamin K should be given to ALL newborns, including preterm infants, within one hour of birth regardless of gestational age. 1

• The American Academy of Pediatrics recommends a single intramuscular dose of 0.5 to 1 mg phytonadione (Vitamin K) within one hour of birth for all newborns, including preterm infants 1
• This prevents hemorrhagic disease of the newborn, which is particularly critical in preterm infants who have lower vitamin K-dependent clotting factors than term infants 2
• For high-risk neonates (including premature infants), the intramuscular route is preferred over oral administration 2
• Preterm infants may require repeated doses depending on their clinical condition, particularly if they have birth asphyxia, difficult delivery, or any illness delaying feeding 2

Hepatitis B Vaccine Administration

The timing of Hepatitis B vaccination depends critically on the mother's HBsAg status and the infant's birth weight.

If Mother is HBsAg-Negative:

• Delay the first dose of Hepatitis B vaccine until hospital discharge or 1 month of age for infants weighing <2,000 grams (which a 31-week infant typically is) 3
• This recommendation exists because preterm infants <2,000 grams have significantly decreased immunologic response to Hepatitis B vaccine administered before age 1 month 3
• Research demonstrates that only 11% of infants <1,000 grams and 25% overall achieve seroprotection after two doses when vaccinated in the first week of life 4
• The birth dose should NOT be counted as part of the vaccine series for these infants—they will need 3 additional doses after the delayed first dose 3

If Mother is HBsAg-Positive or Unknown:

• Administer BOTH Hepatitis B vaccine AND HBIG within 12 hours of birth, regardless of birth weight 3
• Give them at different injection sites (separate limbs) 3
• The birth dose does NOT count toward the vaccine series—the infant needs 3 additional doses for a total of 4 doses 3
• The final dose must not be administered before 24 weeks (164 days) of age 3

Critical Timing Considerations

• The minimum age for the final dose of Hepatitis B vaccine is 24 weeks (approximately 6 months) regardless of when the series was started 3
• For preterm infants born to HBsAg-negative mothers, delaying vaccination until hospital discharge results in a 90% seroconversion rate, which is acceptable 5
• Nonresponders to the vaccine series are more likely to be infants with poor weight gain in the first 6 months of life, so monitor growth carefully 4

Common Pitfalls to Avoid

• Do not withhold Vitamin K from preterm infants—they are at higher risk for hemorrhagic complications and require immediate prophylaxis 1, 2
• Do not give the birth dose of Hepatitis B vaccine to a <2,000 gram infant born to an HBsAg-negative mother—this wastes a dose due to poor immunogenicity 3, 4
• Do not use combination vaccines (like Vaxelis) for the birth dose—only monovalent Hepatitis B vaccine is appropriate 6
• Ensure proper documentation of maternal HBsAg status is placed in the infant's medical record and communicated if the infant is transferred to another facility 3

Safety Profile

• Hepatitis B vaccine is well-tolerated in preterm infants from 6 weeks of age onwards, with mostly minor adverse events such as injection site reactions and transient temperature instability 7
• Serious adverse events are rare (~1%) and occur predominantly in high-risk populations 7
• The vaccine is safe and effective when administered according to these weight-based and timing guidelines 8, 7