1. Background

• Hemorrhagic Disease of the Newborn (HDNB) was first described by C.W. Townsend (Arch Pediatric 11:559-565) in 1894
• Vitamin K facilitates the post-transcription gamma carboxylation of glutamic acid residues on Factors II, VII, IX, and X. This carboxylation helps bind these clotting factors to phospholipid receptor sites on the surface of platelets which leads to the activation of the coagulation pathway. In the absence of this carboxylation, these vitamin K-dependent clotting factors cannot bind to the platelets and thus the coagulation process becomes defective.

2. Pathogenesis

• there are a number of factors which contribute to a transient reduction in the availability of vitamin K to the infant in the newborn period:

  1. Fetal

  • reduced stores of vitamin K
  • absence of the bacterial flora which normally synthesize vitamin K
  • functional immaturity of the liver (where the vitamin- K-dependent factors are synthesized)

  2. Maternal

  • lack of free vitamin K in the serum
  • drug ingestion during pregnancy which interferes with vitamin K metabolism
    • anticonvulsants (phenobarbital, phenytoin)
    • anticoagulants (aspirin)
  • reduced availability of vitamin K in the newborn period -> transient vitamin K-dependent clotting factor deficiency which peaks between 48-72 hours after birth with a gradual return to normal by 7-10 days of age -> tendency to bleed during the first week of life
  • in premature infants, the degree and duration of factor deficiency may increase resulting in a more severe and prolonged bleeding tendency

1. Hematological Manifestations

• gastrointestinal hemorrhage
• prolonged bleeding after circumcision
• epistaxis (nose bleeds)
• ecchymosis (bruising)
• intracranial hemorrhage

2. Types of HDNB

1. Serum

• prolonged INR, PT, PTT
• decreased levels of Factors II, VII, IX, and X
• normal CBC and bleeding time

1. Prophylactic Therapy

• administer Vitamin K1 to all newborns within 6 hours of birth
  • Vitamin K1 1.0 mg IM (birthweight greater than 1500 gms)
  • Vitamin K1 0.5 mg IM (birthweight less than 1500 gms)
• for parents who refuse the IM route, give 2.0 mg po of Vitamin K1 (the parenteral form) at the first feed, again between 2-4 weeks of age, and then once more between 6-8 weeks of age
• recent analysis of available evidence (see additional references below) suggests that the IM route is more effective in preventing Late HDNB than the oral route

2. Premature Infants

• administration of vitamin K may be less effective in preventing HDNB
• if bleeding does occur, the infant may need to be treated with IV Vitamin K1 and/or fresh frozen plasma

3. Early HDNB

• treat with IV Vitamin K1 and/or fresh frozen plasma

1. Paediatrics and Child Health 2(6): 429-431 (1997).

2. Hirsh, J. and E.A. Brain. Hemostasis and Thrombosis. A Conceptual Approach (2nd Edition). p. 81-82 (1983).