Vitamin K deficiency bleeding cases among U.S. infants rose sharply, from 189 in 2017 to 903 in 2024 and 1,764 in 2025, according to a study of health records for more than 11 million babies; most affected infants had not received the vitamin K shot.

The shot has been standard care since 1961 because newborns have low levels of vitamin K, which helps blood clot, and breast milk provides only small amounts; the CDC continues to recommend it.

The stakes are serious: babies who miss the shot are 81 times more likely to develop the disorder, which can cause severe bleeding, including in the brain; about one in five babies who suffer a stroke from it die, and 40% of survivors have lasting brain or nerve problems.

The most serious form typically emerges two to eight weeks after birth, often in exclusively breastfed babies, and can cause a major bleed without warning signs.

Meanwhile, newborns’ receipt of the shot fell from 98% to 95%.

A Reuters analysis of more than 1 million births found refusals rose by more than 57% from January through June 2026; researchers said the rise coincides with growing vaccine hesitancy and skepticism about newborn interventions.

Researchers said they could not establish why more parents are refusing the shot, and noted that some mistakenly believe it is a vaccine, though it is not.

Oral vitamin K is available, but it is considered less effective and may require repeated doses; study authors said offering it could reduce harm when parents decline the injection.

The CDC does not track vitamin K shot refusals or bleeding rates, prompting Representative Kim Schrier and Senator Angela Alsobrooks to call in June for the agency to begin tracking these events.

Researchers and pediatricians called for clear public-health messaging, while a Health and Human Services spokesperson did not say whether the agency would begin tracking refusals or bleeding events.

The U.S. Department of Health and Human Services supported CDC advice to give the shot within six hours of birth, while attributing declining trust to pandemic-era mandates and mixed messages under the Biden administration.