Why is vitamin K given to newborns after birth?

• A. To prevent anemia in infancy
• B. To prevent hemorrhagic disease of the newborn by aiding clotting factor production.
• C. To enhance bone growth
• D. To improve immune response

Answer: (B)

Vitamin K is given to newborns to prevent hemorrhagic disease of the newborn by enabling the liver to produce clotting factors. In newborns, gut bacteria that normally produce vitamin K are not yet established, and the liver is immature, so storing and activating these factors is limited. Vitamin K is essential for gamma-carboxylation of clotting factors II, VII, IX, and X; without it, these factors can’t form effective clots, which increases the risk of dangerous bleeding, including within the brain. Giving vitamin K shortly after birth provides the necessary cofactor for clotting, markedly reducing the chance of serious hemorrhage. It’s not about preventing anemia, boosting bone growth, or improving immune response.