Q: Why do newborns get a vitamin K shot right after birth?
A: Newborn babies are born with very low levels of vitamin K, a nutrient the body needs to form blood clots and stop bleeding. Without enough vitamin K, babies are at risk for a condition called vitamin K deficiency bleeding, or VKDB. While uncommon, it can be devastating. Infants can develop bleeding in the intestines or even the brain during the first few weeks or months of life. In severe cases, it has led to permanent brain injury or death.
The vitamin K shot has been standard medical practice in the United States since the early 1960s and is recommended by the American Academy of Pediatrics and the Centers for Disease Control and Prevention. It is not a vaccine. It is simply a vitamin supplement given as a one-time injection shortly after birth.
Breast milk naturally contains only small amounts of vitamin K, and babies do not get enough through the placenta before birth. That means even healthy newborns can quickly become deficient. The injection provides protection during those vulnerable first months of life when bleeding complications are most likely to occur.
Recently, researchers analyzing over five million U.S. births found that more parents are declining the shot. The refusal rate increased from about 3% in 2017 to more than 5% in 2024. This trend seems fueled in part by misinformation online and confusion between vitamin K and other childhood vaccines.