What the new studies found
Two studies published Thursday in JAMA and JAMA Pediatrics report that life-threatening bleeding among American infants has increased sharply since 2017. Over the same period, more parents have turned down the vitamin K injection routinely offered to newborns. According to the report, they are the first studies to show bleeding rates and refusals rising together.
Newborns do not have enough vitamin K, a nutrient the body needs to clot blood. Giving the shot at birth has been standard practice since 1961.
The JAMA Pediatrics study, led by researchers at Virginia Commonwealth University, reviewed medical records for 11 million infants aged six months and younger from 2017 through 2025. The share of newborns receiving the shot slipped from 97.7% to 95%. Meanwhile the rate of vitamin K deficiency bleeding nearly quadrupled and appeared to be speeding up. The records showed 5,217 bleeding events in total.
Risks for babies who went without
The JAMA study, led by Dr. Kristan Scott and colleagues at the Children's Hospital of Philadelphia, drew on records for more than 5.2 million U.S. infants born from 2017 to 2025. The share of newborns who did not get the shot more than doubled, from 3.1% in 2017 to 6.8% in 2025. At the end of 2024 the figure had been 5.1%.
Babies who missed the injection had a 47% higher risk of bleeding during their first six months. Their risk of bleeding in the brain was more than double that of vaccinated peers, as was their risk of dying with a bleeding diagnosis during the hospital stay after birth. The authors estimated that one additional bleeding event occurs for every 114 newborns who go without the shot.
An earlier analysis by Scott's team, published in JAMA in December, had put the 2024 refusal share above 5%, a 77% increase over 2017.
Causation, caution and a sharp recent rise
Dr. Steven Woolf, an epidemiologist at Virginia Commonwealth University whose study appeared in JAMA Pediatrics, said the studies cannot prove that skipped shots caused the bleeding. He said it is still significant that bleeding rose so dramatically while refusals and deficiencies increased. "Now we're stepping away from that and we're seeing the consequences," he said of the long-standing standard of care.
Woolf also said, "The rate in 2025 was approximately double what it was in 2024." His team noted that the 2025 peak coincides with declining trust in public health after the COVID pandemic, growing vaccine hesitancy and more parental doubt about newborn interventions.
Newer figures point to further movement. An exclusive analysis for Reuters by the health data company Truveta covered more than 1 million births nationwide. It found refusals accelerating sharply in early 2026, up by more than 57% from January through June.
Policy backdrop and calls for tracking
Because the shot has been routine for so long, the Centers for Disease Control and Prevention does not follow refusal rates or bleeding events. Refusals have risen steadily since the pandemic but have sped up under Health Secretary Robert F. Kennedy Jr., who spent decades fostering distrust of vaccines before taking office. He has since removed childhood recommendations for six vaccines. Changes to the childhood vaccination schedule are on hold because of a legal challenge. Health experts say the mixed messages have left many parents doubting routine newborn care, vitamin K included.
A Department of Health and Human Services spokesperson said the CDC still recommends the shot for newborns. The spokesperson declined to say whether the agency will begin tracking refusals or bleeding. In June, Rep. Kim Schrier of Washington and Sen. Angela Alsobrooks of Maryland, both Democrats, urged the CDC to start monitoring these bleeding events.
Dr. Elizabeth Wolf, a pediatrician at Children's Hospital of Richmond who led the VCU study, said the results call for clear messaging from every level of public health about vitamin K. "Similar to the recent measles outbreaks, we are seeing the real-world implications of growing mistrust of doctors and public health professionals," she said.
