This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
Feature of hemorrhagic disease of new born is – 
Select and explain. 
A. Prolonged prothrombin time, B. Defective platelet count, C. Prolonged bleeding time, D. Prolonged thrombin time
A: Prolonged prothrombin time
Answer: A: Prolonged prothrombin time 
Explanation: Normal new borns are moderately deficient in vitamin K.
This deficiency increases on 3rd to 5th day when, vitamin K level falls further. The serum level of vitamin K starts increasing from 13th to 15th day of life and achieves adult level at 3 months.
This is normal, and does not produce any bleeding.
In hemorrhagic disease of the newborn there is delay in achieving the normal vitamin K level.

Clinical Features

Vitamin K deficiency produces severe bleeding.
Bleeding occurs from umbilical cord stump on 2nd/3rd day after birth.
Intracranial bleding and large intramuscular hemorrhages may occur.
Increased prothronzbin time and increased partial thromboplastin time.

T/T

Parenteral vitamin K therapy.