Hemorrhagic Disease of the Newborn (HDNB) can be classified based on the time of clinical onset.

Time of Onset


Typical Cause

<= 24 hours old

early onset

maternal drug that affects vitamin K function or maternal vitamin K deficiency

2 to 7 days old


failure to give a prophylactic dose of vitamin K after delivery, delayed feeding

3 to 8 weeks old

late onset

inadequate vitamin K intake or malabsorption


Neonates usually have low vitamin K levels at birth because delivery of vitamin K across the placental barrier is poor.


Maternal drugs that may affect vitamin K function:

(1) antituberculous (isoniazid)

(2) anticonvulsant (paper of Kazmin et al indicates that this is unlikely)


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